Therapeutic utility of human umbilical cord-derived mesenchymal stem cells-based approaches in pulmonary diseases:Recent advancements and prospects

Pulmonary diseases across all ages threaten millions of people and have emerged as one of the major public health issues worldwide.For diverse disease con-ditions,the currently available approaches are focused on alleviating clinical symptoms and delaying disease progression but have not shown significant therapeutic effects in patients with lung diseases.Human umbilical cord-derived mesenchymal stem cells(UC-MSCs)isolated from the human UC have the capacity for self-renewal and multilineage differentiation.Moreover,in recent years,these cells have been demonstrated to have unique advantages in the treatment of lung diseases.We searched the Public Clinical Trial Database and found 55 clinical trials involving UC-MSC therapy for pulmonary diseases,including coronavirus disease 2019,acute respiratory distress syndrome,bron-chopulmonary dysplasia,chronic obstructive pulmonary disease,and pulmonary fibrosis.In this review,we summarize the characteristics of these registered clinical trials and relevant published results and explore in depth the challenges and opportunitiesfaced in clinical application.Moreover,the underlying mole-cular mechanisms involved in UC-MSC-based therapy for pulmonary diseases are also analyzed in depth.In brief,this comprehensive review and detailed analysis of these clinical trials can be expected to provide a scientific reference for future large-scale clinical application.

Expansion of human umbilical cord derived mesenchymal stem cells in regenerative medicine

BACKGROUND Stem cells are undifferentiated cells that possess the potential for self-renewal with the capacity to differentiate into multiple lineages.In humans,their limited numbers pose a challenge in fulfilling the necessary demands for the regeneration and repair of damaged tissues or organs.Studies suggested that mesenchymal stem cells(MSCs),necessary for repair and regeneration via transplantation,require doses ranging from 10 to 400 million cells.Furthermore,the limited expansion of MSCs restricts their therapeutic application.AIM To optimize a novel protocol to achieve qualitative and quantitative expansion of MSCs to reach the targeted number of cells for cellular transplantation and minimize the limitations in stem cell therapy protocols.METHODS Human umbilical cord(hUC)tissue derived MSCs were obtained and re-cultured.These cultured cells were subjected to the following evaluation pro-cedures:Immunophenotyping,immunocytochemical staining,trilineage differentiation,population doubling time and number,gene expression markers for proliferation,cell cycle progression,senescence-associatedβ-galactosidase assay,human telomerase reverse transcriptase(hTERT)expression,mycoplasma,cytomegalovirus and endotoxin detection.RESULTS Analysis of pluripotent gene markers Oct4,Sox2,and Nanog in recultured hUC-MSC revealed no significant differences.The immunophenotypic markers CD90,CD73,CD105,CD44,vimentin,CD29,Stro-1,and Lin28 were positively expressed by these recultured expanded MSCs,and were found negative for CD34,CD11b,CD19,CD45,and HLA-DR.The recultured hUC-MSC population continued to expand through passage 15.Proliferative gene expression of Pax6,BMP2,and TGFb1 showed no significant variation between recultured hUC-MSC groups.Nevertheless,a significant increase(P<0.001)in the mitotic phase of the cell cycle was observed in recultured hUC-MSCs.Cellular senescence markers(hTERT expression andβ-galactosidase activity)did not show any negative effect on recultured hUC-MSCs.Additionally,quality control assessments consistently confirmed the absence of mycoplasma,cytomegalovirus,and endotoxin contamination.CONCLUSION This study proposes the development of a novel protocol for efficiently expanding stem cell population.This would address the growing demand for larger stem cell doses needed for cellular transplantation and will significantly improve the feasibility of stem cell based therapies.

Human umbilical cord mesenchymal stem cells derivedexosomes on VEGF-A in hypoxic-induced mice retinal astrocytes and mice model of retinopathy of prematurity

AIM:To observe the effect of human umbilical cord mesenchymal stem cells(hUCMSCs)secretions on the relevant factors in mouse retinal astrocytes,and to investigate the effect of hUCMSCs on the expression of vascular endothelial growth factor-A(VEGF-A)and to observe the therapeutic effect on the mouse model of retinopathy of prematurity(ROP).METHODS:Cultured hUCMSCs and extracted exosomes from them and then retinal astrocytes were divided into control group and hypoxia group.MTT assay,flow cytometry,reverse transcription-polymerase chain reaction(RT-PCR)and Western blot were used to detect related indicators.Possible mechanisms by which hUCMSCs exosomes affect VEGF-A expression in hypoxia-induced mouse retinal astrocytes were explored.At last,the efficacy of exosomes of UCMSCs in a mouse ROP model was explored.Graphpad6 was used to comprehensively process data information.RESULTS:The secretion was successfully extracted from the culture supernatant of hUCMSCs by gradient ultracentrifugation.Reactive oxygen species(ROS)and hypoxia inducible factor-1α(HIF-1α)of mice retinal astrocytes under different hypoxia time and the expression level of VEGF-A protein and VEGF-A mRNA increased,and the ROP cell model was established after 6h of hypoxia.The secretions of medium and high concentrations of hUCMSCs can reduce ROS and HIF-1α,the expression levels of VEGF-A protein and VEGF-A mRNA are statistically significant and concentration dependent.Compared with the ROP cell model group,the expression of phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/mammalian target of rapamycin(mTOR)signal pathway related factors in the hUCMSCs exocrine group is significantly decreased.The intravitreal injection of the secretions of medium and high concentrations of hUCMSCs can reduce VEGF-A and HIF-1αin ROP model tissues.HE staining shows that the number of retinal neovascularization in ROP mice decreases with the increase of the dose of hUCMSCs secretion.CONCLUSION:In a hypoxia induced mouse retinal astrocyte model,hUCMSCs exosomes are found to effectively reduce the expression of HIF-1αand VEGF-A,which are positively correlated with the concentration of hUCMSCs exosomes.HUCMSCs exosomes can effectively reduce the number of retinal neovascularization and the expression of HIF-1αand VEGF-A proteins in ROP mice,and are positively correlated with drug dosage.Besides,they can reduce the related factors on the PI3K/AKT/mTOR signaling pathway.

Effects of miR-214-5p and miR-21-5p in hypoxic endometrial epithelial-cell-derived exosomes on human umbilical cord mesenchymal stem cells

BACKGROUND Thin endometrium seriously affects endometrial receptivity,resulting in a significant reduction in embryo implantation,and clinical pregnancy and live birth rates,and there is no gold standard for treatment.The main pathophysiological characteristics of thin endometrium are increased uterine arterial blood flow resistance,angiodysplasia,slow growth of the glandular epithelium,and low expression of vascular endothelial growth factor,resulting in endometrial epithelial cell(EEC)hypoxia and endometrial tissue aplasia.Human umbilical cord mesenchymal stem cells(HucMSCs)promote repair and regeneration of damaged endometrium by secreting microRNA(miRNA)-carrying exosomes.However,the initiation mechanism of HucMSCs to repair thin endometrium has not yet been clarified.AIM To determine the role of hypoxic-EEC-derived exosomes in function of HucMSCs and explore the potential mechanism.METHODS Exosomes were isolated from normal EECs(EEC-exs)and hypoxia-damaged EECs(EECD-exs),before characterization using Western blotting,nanoparticletracking analysis,and transmission electron microscopy.HucMSCs were cocultured with EEC-exs or EECD-exs and differentially expressed miRNAs were determined using sequencing.MiR-21-5p or miR-214-5p inhibitors or miR-21-3p or miR-214-5p mimics were transfected into HucMSCs and treated with a signal transducer and activator of transcription 3(STAT3)activator or STAT3 inhibitor.HucMSC migration was assessed by Transwell and wound healing assays.Differentiation of HucMSCs into EECs was assessed by detecting markers of stromal lineage(Vimentin and CD13)and epithelial cell lineage(CK19 and CD9)using Western blotting and immunofluorescence.The binding of the miRNAs to potential targets was validated by dual-luciferase reporter assay.RESULTS MiR-21-5p and miR-214-5p were lowly expressed in EECD-ex-pretreated HucMSCs.MiR-214-5p and miR-21-5p inhibitors facilitated the migratory and differentiative potentials of HucMSCs.MiR-21-5p and miR-214-5p targeted STAT3 and protein inhibitor of activated STAT3,respectively,and negatively regulated phospho-STAT3.MiR-21-5p-and miR-214-5p-inhibitor-induced promotive effects on HucMSC function were reversed by STAT3 inhibition.MiR-21-5p and miR-214-5p overexpression repressed HucMSC migration and differentiation,while STAT3 activation reversed these effects.CONCLUSION Low expression of miR-21-5p/miR-214-5p in hypoxic-EEC-derived exosomes promotes migration and differentiation of HucMSCs into EECs via STAT3 signaling.Exosomal miR-214-5p/miR-21-5p may function as valuable targets for thin endometrium.

Mesenchymal stem cells derived from human placenta suppress allogeneic umbilical cord blood lymphocyte proliferation

Human placenta-derived mononuclear cells （MNC） were isolated by a Percoll density gradient and cultured in mesenchymal stem cell （MSC） maintenance medium. The homogenous layer of adherent cells exhibited a typical fibroblastlike morphology, a large expansive potential, and cell cycle characteristics including a subset of quiescent cells. In vitro differentiation assays showed the tripotential differentiation capacity of these cells toward adipogenic, osteogenic and chondrogenic lineages. Flow cytometry analyses and immunocytochemistry stain showed that placental MSC was a homogeneous cell population devoid of hematopoietic cells, which uniformly expressed CD29, CD44, CD73, CD105, CD166, laminin, fibronectin and vimentin while being negative for expression of CD31, CD34, CD45 and m-smooth muscle actin. Most importantly, immuno-phenotypic analyses demonstrated that these cells expressed class Ⅰ major histocompatibility complex （MHC-I）, but they did not express MHC-Ⅱ molecules. Additionally these cells could suppress umbilical cord blood （UCB） lymphocytes proliferation induced by cellular or nonspecific mitogenic stimuli. This strongly implies that they may have potential application in allograft transplantation. Since placenta and UCB are homogeneous, the MSC derived from human placenta can be transplanted combined with hematopoietic stem cells （HSC） from UCB to reduce the potential graft-versus-host disease （GVHD） in recipients.

Brain-derived neurotrophic factor induces neuron-like cellular differentiation of mesenchymal stem cells derived from human umbilical cord blood cells in vitro

Human umbilical cord blood was collected from full-term deliveries scheduled for cesarean section. Mononuclear cells were isolated, amplified and induced as mesenchymal stem cells. Isolated mesenchymal stem cells tested positive for the marker CD29, CD44 and CD105 and negative for typical hematopoietic and endothelial markers. Following treatment with neural induction medium containing brain-derived neurotrophic factor for 7 days, the adherent cells exhibited neuron-like cellular morphology. Immunohistochemical staining and reverse transcription-PCR revealed that the induced mesenchymal stem cells expressed the markers for neuron-specific enolase and neurofilament. The results demonstrated that human umbilical cord blood-derived mesenchymal stem cells can differentiate into neuron-like cells induced by brain-derived neurotrophic factor in vitro.

Human umbilical cord blood-derived mesenchymal stem cells promote regeneration of crush-injured rat sciatic nerves

Several studies have demonstrated that human umbilical cord blood-derived mesenchymal stem cells can promote neural regeneration following brain injury. However, the therapeutic effects of human umbilical cord blood-derived mesenchymal stem cells in guiding peripheral nerve regeneration remain poorly understood. This study was designed to investigate the effects of human umbilical cord blood-derived mesenchymal stem cells on neural regeneration using a rat sciatic nerve crush injury model. Human umbilical cord blood-derived mesenchymal stem cells （1 ~ 106） or a PBS control were injected into the crush-injured segment of the sciatic nerve. Four weeks after cell injection, brain-derived neurotrophic factor and tyrosine kinase receptor B mRNA expression at the lesion site was increased in comparison to control. Furthermore, sciatic function index, Fluoro Gold-labeled neuron counts and axon density were also significantly increased when compared with control. Our results indicate that human umbilical cord blood-derived mesenchvmal stem cells promote the functinnal r~.RcJv^rv nf P.n I^h-inillr^4 ~r^i~tit, n^r~e

Functional recovery and microenvironmental alterations in a rat model of spinal cord injury following human umbilical cord blood-derived mesenchymal stem cells transplantation

BACKGROUND： Transplantation of human umbilical cord blood-derived mesenchymal stem cells （MSCs） has been shown to benefit spinal cord injury （SCI） repair. However, mechanisms of microenvironmental regulation during differentiation of transplanted MSCs remain poorly understood. OBJECTIVE： To observe changes in nerve growth factor （NGF）, brain-derived neurotrophic factor （BDNF）, and interleukin-8 （IL-8） expression following transplantation of human umbilical cord-derived MSCs, and to explore the association between microenvironment and neural functional recovery following MSCs transplantation. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Department of Orthopedics, First Affiliated Hospital of Soochow University from April 2005 to March 2007. MATERIALS： Human cord blood samples were provided by the Department of Gynecology and Obstetrics, First Affiliated Hospital of Soochow University. Written informed consent was obtained. METHODS： A total of 62 Wister rats were randomly assigned to control （n = 18）, model （n = 22, SCI ＋ PBS）, and transplantation （n = 22, SCI ＋ MSCs） groups. The rat SCI model was established using the weight compression method. MSCs were isolated from human umbilical cord blood and cultured in vitro for several passages. 5-bromodeoxyuridine （BrdU）-Iabeled MSCs （24 hours before injection） were intravascularly transplanted. MAIN OUTCOME MEASURES： The rats were evaluated using the Basso, Beattie and Bresnahan （BBB） locomotor score and inclined plane tests. Transplanted cells were analyzed following immunohistochemistry. Enzyme-linked immunosorbant assay was performed to determine NGF, BDNF, and IL-8 levels prior to and after cell transplantation. RESULTS： A large number of BrdU-positive MSCs were observed in the SCI region of the transplantation group, and MSCs were evenly distributed in injured spinal cord tissue 1 week after transplantation. BBB score and inclined plane test results revealed significant functional improvement in the transplantation group compared to the model group （P 〈 0.05）, which was maintained for 2-3 weeks. Compared to the model group, NGF and BDNF levels were significantly increased in the injured region following MSCs transplantation at 3 weeks （P 〈 0.05）, but IL-8 levels remained unchanged （P 〉 0.05）. CONCLUSION： MSCs transplantation increased NGF and BDNF expression in injured spinal cord tissue. MSCs could promote neurological function recovery in SCI rats by upregulating NGF expression and improving regional microenvironments.

Prospects for the therapeutic development of umbilical cord bloodderived mesenchymal stem cells

Umbilical cord blood(UCB)is a primitive and abundant source of mesenchymal stem cells(MSCs).UCB-derived MSCs have a broad and efficient therapeutic capacity to treat various diseases and disorders.Despite the high latent selfrenewal and differentiation capacity of these cells,the safety,efficacy,and yield of MSCs expanded for ex vivo clinical applications remains a concern.However,immunomodulatory effects have emerged in various disease models,exhibiting specific mechanisms of action,such as cell migration and homing,angiogenesis,anti-apoptosis,proliferation,anti-cancer,anti-fibrosis,anti-inflammation and tissue regeneration.Herein,we review the current literature pertaining to the UCB-derived MSC application as potential treatment strategies,and discuss the concerns regarding the safety and mass production issues in future applications.

Human umbilical cord blood stem cells and brainderived neurotrophic factor for optic nerve injury: a biomechanical evaluation

Treatment for optic nerve injury by brain-derived neurotrophic factor or the transplantation of human umbilical cord blood stem cells has gained progress, but analysis by biomechanical indicators is rare. Rabbit models of optic nerve injury were established by a clamp. At 7 days after injury, the vitreous body received a one-time injection of 50 μg brain-derived neurotrophic factor or 1 × 10^6 human umbilical cord blood stem cells. After 30 days, the maximum load, maximum stress, maximum strain, elastic limit load, elastic limit stress, and elastic limit strain had clearly improved in rabbit models of optical nerve injury after treatment with brain-derived neurotrophic factor or human umbilical cord blood stem cells. The damage to the ultrastructure of the optic nerve had also been reduced. These findings suggest that human umbilical cord blood stem cells and brain-derived neurotrophic factor effectively repair the injured optical nerve, improve biomechanical properties, and contribute to the recovery after injury.

High tibial osteotomy with human umbilical cord blood-derived mesenchymal stem cells implantation for knee cartilage regeneration

BACKGROUND High tibial osteotomy(HTO)is a well-established method for the treatment of medial compartment osteoarthritis of the knee with varus deformity.However,HTO alone cannot adequately repair the arthritic joint,necessitating cartilage regeneration therapy.Cartilage regeneration procedures with concomitant HTO are used to improve the clinical outcome in patients with varus deformity.AIM To evaluate cartilage regeneration after implantation of allogenic human umbilical cord blood-derived mesenchymal stem cells(hUCB-MSCs)with concomitant HTO.METHODS Data for patients who underwent implantation of hUCB-MSCs with concomitant HTO were evaluated.The patients included in this study were over 40 years old,had a varus deformity of more than 5°,and a full-thickness International Cartilage Repair Society(ICRS)grade IV articular cartilage lesion of more than 4 cm2 in the medial compartment of the knee.All patients underwent second-look arthroscopy during hardware removal.Cartilage regeneration was evaluated macroscopically using the ICRS grading system in second-look arthroscopy.We also assessed the effects of patient characteristics,such as trochlear lesions,age,and lesion size,using patient medical records.RESULTS A total of 125 patients were included in the study,with an average age of 58.3±6.8 years(range:43-74 years old);95(76%)were female and 30(24%)were male.The average hip-knee-ankle(HKA)angle for measuring varus deformity was 7.6°±2.4°(range:5.0-14.2°).In second-look arthroscopy,the status of medial femoral condyle(MFC)cartilage was as follows:73(58.4%)patients with ICRS grade I,37(29.6%)with ICRS grade II,and 15(12%)with ICRS grade III.No patients were staged with ICRS grade IV.Additionally,the scores[except International Knee Documentation Committee(IKDC)at 1 year]of the ICRS grade I group improved more significantly than those of the ICRS grade II and III groups.CONCLUSION Implantation of hUCB-MSCs with concomitant HTO is an effective treatment for patients with medial compartment osteoarthritis and varus deformity.Regeneration of cartilage improves the clinical outcomes for the patients.

Human umbilical cord blood-derived stem cells and brain-derived neurotrophic factor protect injured optic nerve:viscoelasticity characterization

The optic nerve is a viscoelastic solid-like biomaterial.Its normal stress relaxation and creep properties enable the nerve to resist constant strain and protect it from injury.We hypothesized that stress relaxation and creep properties of the optic nerve change after injury.Moreover,human brain-derived neurotrophic factor or umbilical cord blood-derived stem cells may restore these changes to normal.To validate this hypothesis,a rabbit model of optic nerve injury was established using a clamp approach.At 7 days after injury,the vitreous body received a one-time injection of 50 μg human brain-derived neurotrophic factor or 1 × 106 human umbilical cord blood-derived stem cells.At 30 days after injury,stress relaxation and creep properties of the optic nerve that received treatment had recovered greatly,with pathological changes in the injured optic nerve also noticeably improved.These results suggest that human brain-derived neurotrophic factor or umbilical cord blood-derived stem cell intervention promotes viscoelasticity recovery of injured optic nerves,and thereby contributes to nerve recovery.

Repair of a large patellar cartilage defect using human umbilical cord blood-derived mesenchymal stem cells:A case report

BACKGROUND Patellar dislocation may cause cartilage defects of various sizes.Large defects commonly require surgical treatment;however,conventional treatments are problematic.CASE SUMMARY A 15-year-old male with a large patellar cartilage defect due to patellar dislocation was treated via human umbilical cord blood-derived mesenchymal stem cell(hUCB-MSC)implantation.To our knowledge,this is the first report of this treatment for this purpose.The patient recovered well as indicated by good visual analog scale,International Knee Documentation Committee and McMaster Universities Osteoarthritis Index scores.Magnetic resonance imaging showed cartilage regeneration 18 mo postoperatively.CONCLUSION Umbilical cord blood-derived hUCB-MSCs may be a useful treatment option for the repair of large patellar cartilage defects.

Electro-acupuncture at Conception and Governor vessels and transplantation of umbilical cord bloodderived mesenchymal stem cells for treating cerebral ischemia/reperfusion injury

Mesenchymal stem cell transplantation is a novel means of treating cerebral ischemia/reper- fusion, and can promote angiogenesis and neurological functional recovery. Acupuncture at Conception and Governor vessels also has positive effects as a treatment for cerebral ischemia/ reperfusion. Therefore, we hypothesized that electro-acupuncture at Conception and Governor vessels plus mesenchymal stem cell transplantation may have better therapeutic effects on the promotion of angiogenesis and recovery of neurological function than either treatment alone. In the present study, human umbilical cord blood-derived mesenchymal stem cells were isolated, cultured, identified and intracranially transplanted into the striatum and subcortex of rats at 24 hours following cerebral ischemia/reperfusion. Subsequently, rats were electro-acupunctured at Conception and Governor vessels at 24 hours after transplantation. Modified neurological severity scores and immunohistochemistry findings revealed that the combined interventions of electro-acupuncture and mesenchymal stem cell transplantation clearly improved neurological impairment and up-regulated vascular endothelial growth factor expression around the isch- emic focus. The combined intervention provided a better outcome than mesenchymal stem cell transplantation alone. These findings demonstrate that electro-acupuncture at Conception and Governor vessels and mesenchymal stem cell transplantation have synergetic effects on promot- ing neurological function recovery and angiogenesis in rats after cerebral ischemia/reperfusion.

Human umbilical cord mesenchymal stem cell-derived exosomes loaded into a composite conduit promote functional recovery after peripheral nerve injury in rats

Complete transverse injury of peripheral nerves is challenging to treat.Exosomes secreted by human umbilical cord mesenchymal stem cells are considered to play an important role in intercellular communication and regulate tissue regeneration.In previous studies,a collagen/hyaluronic acid sponge was shown to provide a suitable regeneration environment for Schwann cell proliferation and to promote axonal regeneration.This three-dimensional(3D)composite conduit contains a collagen/hyaluronic acid inner sponge enclosed in an electrospun hollow poly(lactic-co-glycolic acid)tube.However,whether there is a synergy between the 3D composite conduit and exosomes in the repair of peripheral nerve injury remains unknown.In this study,we tested a comprehensive strategy for repairing long-gap(10 mm)peripheral nerve injury that combined the 3D composite conduit with human umbilical cord mesenchymal stem cell-derived exosomes.Repair effectiveness was evaluated by sciatic functional index,sciatic nerve compound muscle action potential recording,recovery of muscle mass,measuring the cross-sectional area of the muscle fiber,Masson trichrome staining,and transmission electron microscopy of the regenerated nerve in rats.The results showed that transplantation of the 3D composite conduit loaded with human umbilical cord mesenchymal stem cell-derived exosomes promoted peripheral nerve regeneration and restoration of motor function,similar to autograft transplantation.More CD31-positive endothelial cells were observed in the regenerated nerve after transplantation of the loaded conduit than after transplantation of the conduit without exosomes,which may have contributed to the observed increase in axon regeneration and distal nerve reconnection.Therefore,the use of a 3D composite conduit loaded with human umbilical cord mesenchymal stem cell-derived exosomes represents a promising cell-free therapeutic option for the treatment of peripheral nerve injury.

Safety and effect of umbilical cord blood -derived mesenchymal stem cells on apoptosis of human cardiomyocytes

Objective To study the safety and effect of the umbilical cord blood （UCB）-derived mesenchymal stem cells （MSCs） on apoptosis of human cardiomyocytes （HCM）. Methods UCB was collected at the time of delivery with informed consent obtained from 10 donors. The UCB-derived MSCs were treated with 5-azaserube （5-AZA） and were further induced to differentiate into cardiomyocytes. Telomerase activity, G-banding patterns of chromosomal karyotypes, tumor formation in nude mice, RT-PCR, and the effect of inhibiting apoptosis of HCM were investigated. Results MSCs derived from UCB were differentiated into cardiomyocytes in vitro, which possessed telomerase activity after 5-AZA induction, and no abnormal chromosomal karyotypes were observed. Expression of p53, cyclin A, cdk2, ~3 -actin, C-fos, h-TERT and c-myc were similar in MSCs before and after 5-AZA treatment. There was no tumor formation in nude mice after injection of UCB-derived MSCs. UCB-derived MSCs significantly inhibited apoptosis of HCM. Conclusion UCB-derived MSCs are a valuable, safe and effective source of cell-transplantation treatment .

Efficacy of serum-free cultured human umbilical cord mesenchymal stem cells in the treatment of knee osteoarthritis in mice

BACKGROUND We investigated the efficacy of intra-articular injection of human umbilical cord mesenchymal stem cells(hUC-MSCs)for the treatment of osteoarthritis(OA)progression in the knee joint.Although many experimental studies of hUC-MSCs have been published,these studies have mainly used fetal bovine serumcontaining cultures of hUC-MSCs;serum-free cultures generally avoid the shortcomings of serum-containing cultures and are not subject to ethical limitations,have a wide range of prospects for clinical application,and provide a basis or animal experimentation for clinical experiments.AIM To study the therapeutic effects of serum-free hUC-MSCs(N-hUCMSCs)in a mouse model of knee OA.METHODS Fifty-five male C57BL/6 mice were randomly divided into six groups:The blank control group,model control group,serum-containing hUC-MSCs(S-hUCMSC)group,N-hUCMSC group and hyaluronic acid(HA)group.After 9 weeks of modeling,the serum levels of interleukin(IL)-1β and IL-1 were determined.Hematoxylin-eosin staining was used to observe the cartilage tissue,and the Mankin score was determined.Immunohistochemistry and western blotting were used to determine the expression of collagen type II,matrix metalloproteinase(MMP)-1 and MMP-13.RESULTS The Mankin score and serum IL-1 and IL-1β and cartilage tissue MMP-1 and MMP-13 expression were significantly greater in the experimental group than in the blank control group(P<0.05).Collagen II expression in the experimental group was significantly lower than that in the blank control group(P<0.05).The Mankin score and serum IL-1 and IL-1β and cartilage tissue MMP-1 and MMP-13 levels the experimental group were lower than those in the model control group(P<0.05).Collagen II expression in the experimental group was significantly greater than that in the model control group(P<0.05).CONCLUSION N-hUCMSC treatment significantly alleviate the pathological damage caused by OA.The treatment effects of the ShUCMSC group and HA group were similar.

The chimeric mice derived from umbilical cord blood stem cells of EGFP-transgenic mouse

Objective:The chimeric mice were prepared by microinjection of blastocyst cavity using umbilical cord blood stem cells(UCBSCs)of Enhanced Green Fluorescent Protein(EGFP)-transgenic mouse,which was expected to provide a theoretical and experimental basis for the study of in-vivo differentiation of adult stem cells.Methods:Mouse UCBSCs expressing green fluorescence was microinjected into blastocyst cavity and several blastocysts were transferred into uterus of pseudo pregnant mouse.First of all,new-born candidate chimeric mice were observed through feather color.Secondly,the genomic DNA and total RNA were extracted to analyze chimeric rate in several tissues.Finally,flow cytometry was used to detect percentage of green fluorescent cells mice in several tissues.Results:The UCBSCs expressing green fluorescent protein were successfully isolated.After flow cytometry analysis,the proportion of cells expressing green fluorescence was 80.25%.Through microinjection and embryo transfer,we got five white new-born mice and no chimeric feather color was observed.The analyses of PCR and RT-PCR were carried out to detect EGFP gene using six tissues including heart muscle,liver,lung,skin,leg muscle and adipose tissue.The results showed that the leg muscle and adipose tissue of two mice were positive and the other tissues and six tissues of the other 3 mice were all negative.The leg muscle and adipose tissue of two positive mice were digested into single-cells suspension and were carried out flow cytometry analysis.The results showed that the average chimeric rates of leg muscle and adipose tissue of two positive mice were 9.87% and 5.78%,respectively.Conclusions:The results demonstrated that adult UCBSCs could differentiate into leg muscle and adipose tissue in vivo.

Umbilical cord mesenchymal stem cell exosomes alleviate necrotizing enterocolitis in neonatal mice by regulating intestinal epithelial cells autophagy

BACKGROUND Necrotizing enterocolitis(NEC)is a severe gastrointestinal disease that affects premature infants.Although mounting evidence supports the therapeutic effect of exosomes on NEC,the underlying mechanisms remain unclear.AIM To investigate the mechanisms underlying the regulation of inflammatory response and intestinal barrier function by umbilical cord mesenchymal stem cell(UCMSCs)exosomes,as well as their potential in alleviating NEC in neonatal mice.METHODS NEC was induced in 5-d-old C57BL/6 pups through hypoxia and gavage feeding of formula containing lipopolysaccharide(LPS),after which the mice received human UCMSC exosomes(hUCMSC-exos).The control mice were allowed to breastfeed with their dams.Ileal tissues were collected from the mice and analyzed by histopathology and immunoblotting.Colon tissues were collected from NEC neonates and analyzed by immunofluorescence.Molecular biology and cell culture approaches were employed to study the related mechanisms in intestinal epithelial cells.RESULTS We found that autophagy is overactivated in intestinal epithelial cells during NEC,resulting in reduced expression of tight junction proteins and an increased inflammatory response.The ability of hUCMSC-exos to ameliorate NEC in a mouse model was dependent on decreased intestinal autophagy.We also showed that hUCMSC-exos alleviate the inflammatory response and increase migration ability in intestinal epithelial cells induced by LPS.CONCLUSION These results contribute to a better understanding of the protective mechanisms of hUCMSC-exos against NEC and provide a new theoretical and experimental foundation for NEC treatment.These findings also enhance our understanding of the role of the autophagy mechanism in NEC,offering potential avenues for identifying new therapeutic targets.

Preliminary study on the preparation of lyophilized acellular nerve scaffold complexes from rabbit sciatic nerves with human umbilical cord mesenchymal stem cells

BACKGROUND The gold standard of care for patients with severe peripheral nerve injury is autologous nerve grafting;however,autologous nerve grafts are usually limited for patients because of the limited number of autologous nerve sources and the loss of neurosensory sensation in the donor area,whereas allogeneic or xenografts are even more limited by immune rejection.Tissue-engineered peripheral nerve scaffolds,with the morphology and structure of natural nerves and complex biological signals,hold the most promise as ideal peripheral nerve“replacements”.AIM To prepare allogenic peripheral nerve scaffolds using a low-toxicity decellularization method,and use human umbilical cord mesenchymal stem cells(hUCMSCs)as seed cells to cultivate scaffold-cell complexes for the repair of injured peripheral nerves.METHODS After obtaining sciatic nerves from New Zealand rabbits,an optimal acellular scaffold preparation scheme was established by mechanical separation,varying lyophilization cycles,and trypsin and DNase digestion at different times.The scaffolds were evaluated by hematoxylin and eosin(HE)and luxol fast blue(LFB)staining.The maximum load,durability,and elastic modulus of the acellular scaffolds were assessed using a universal material testing machine.The acellular scaffolds were implanted into the dorsal erector spinae muscle of SD rats and the scaffold degradation and systemic inflammatory reactions were observed at 3 days,1 week,3 weeks,and 6 weeks following surgery to determine the histocompatibility between xenografts.The effect of acellular scaffold extracts on fibroblast proliferation was assessed using an MTT assay to measure the cytotoxicity of the scaffold residual reagents.In addition,the umbilical cord from cesarean section fetuses was collected,and the Wharton’s jelly(WJ)was separated into culture cells and confirm the osteogenic and adipogenic differentiation of mesenchymal stem cells(MSCs)and hUC-MSCs.The cultured cells were induced to differentiate into Schwann cells by the antioxidant-growth factor induction method,and the differentiated cells and the myelinogenic properties were identified.RESULTS The experiments effectively decellularized the sciatic nerve of the New Zealand rabbits.After comparing the completed acellular scaffolds among the groups,the optimal decellularization preparation steps were established as follows:Mechanical separation of the epineurium,two cycles of lyophilization-rewarming,trypsin digestion for 5 hours,and DNase digestion for 10 hours.After HE staining,no residual nuclear components were evident on the scaffold,whereas the extracellular matrix remained intact.LFB staining showed a significant decrease in myelin sheath composition of the scaffold compared with that before preparation.Biomechanical testing revealed that the maximum tensile strength,elastic modulus,and durability of the acellular scaffold were reduced compared with normal peripheral nerves.Based on the histocompatibility test,the immune response of the recipient SD rats to the scaffold New Zealand rabbits began to decline3 weeks following surgery,and there was no significant rejection after 6 weeks.The MTT assay revealed that the acellular reagent extract had no obvious effects on cell proliferation.The cells were successfully isolated,cultured,and passaged from human umbilical cord WJ by MSC medium,and their ability to differentiate into Schwann-like cells was demonstrated by morphological and immunohistochemical identification.The differentiated cells could also myelinate in vitro.CONCLUSION The acellular peripheral nerve scaffold with complete cell removal and intact matrix may be prepared by combining lyophilization and enzyme digestion.The resulting scaffold exhibited good histocompatibility and low cytotoxicity.In addition,hUC-MSCs have the potential to differentiate into Schwann-like cells with myelinogenic ability following in vitro induction.