Adipose-derived stem cells and knee osteoarthritis:New perspectives,old concerns

In this editorial,we comment on the paper by Muthu et al published in the recent issue of the journal.This editorial review focusses on the use of adipose-derived stem cells(ADSCs)in knee osteoarthritis treatment.We discuss the differences between the stromal vascular fraction and microfragmented adipose tissue and highlight the results of clinical studies comparing both treatments and the use of hyaluronic acid,platelet-rich plasma,and bone marrow aspirate concentrate.The use of expanded ADSCs is also discussed;moreover,concerns regarding treatment with ADSCs,particularly the heterogeneity of published studies and the need to standardize protocols to explore clinical potential is explored.

Role of adipose tissue grafting and adipose-derived stem cells in peripheral nerve surgery

The application of autologous fat grafting in reconstructive surgery is commonly used to improve functional form.This review aims to provide an overview of the scientific evidence on the biology of adipose tissue,the role of adipose-derived stem cells,and the indications of adipose tissue grafting in peripheral nerve surgery.Adipose tissue is easily accessible through the lower abdomen and inner thighs.Non-vascularized adipose tissue grafting does not support oxidative and ischemic stress,resulting in variable survival of adipocytes within the first 24 hours.Enrichment of adipose tissue with a stromal vascular fraction is purported to increase the number of adipose-derived stem cells and is postulated to augment the long-term stability of adipose tissue grafts.Basic science nerve research suggests an increase in nerve regeneration and nerve revascularization,and a decrease in nerve fibrosis after the addition of adipose-derived stem cells or adipose tissue.In clinical studies,the use of autologous lipofilling is mostly applied to secondary carpal tunnel release revisions with promising results.Since the use of adipose-derived stem cells in peripheral nerve reconstruction is relatively new,more studies are needed to explore safety and long-term effects on peripheral nerve regeneration.The Food and Drug Administration stipulates that adipose-derived stem cell transplantation should be minimally manipulated,enzyme-free,and used in the same surgical procedure,e.g.adipose tissue grafts that contain native adipose-derived stem cells or stromal vascular fraction.Future research may be shifted towards the use of tissue-engineered adipose tissue to create a supportive microenvironment for autologous graft survival.Shelf-ready alternatives could be enhanced with adipose-derived stem cells or growth factors and eliminate the need for adipose tissue harvest.

In vitro differentiation of human adipose-derived adult stromal cells into neuron-like cells in hippocampal astrocyte conditioned medium

BACKGROUND: At present, researches on differentiating from human adipose-derived adult stromal cells (hADASC) to neuron-like cells are focus on inducing by artificial-synthetic compound solution; however, hippocampal astrocyte conditioned medium (HCAM) can induce in vitro differentiation from hADASC to neuron-like cells is still unclear. OBJECTIVE: To observe whether HCAM can induce in vitro differentiation from hADASC to neuron-like cells. DESIGN: Randomized control study. SETTING: Department of Neurology, Taixing People's Hospital; Central Laboratory, North China Coal Medical College. MATERIALS: Donor of adipose tissue was donated by female volunteers suffering from caesarean section in the department of obstetrics & gynecology in our hospital and aged 20-35 years. Adipose tissue was collected from subcutaneous tissue of abdomen during the operation. In addition, 8 male newborn Wistar rats within 24 hours with average body mass of 20 g were provided by Animal Institute of Chinese Academy of Medical Sciences. Rabbit-anti-human Nestin polyclonal antibody, rabbit-anti-human glial fibriliary acidic protein (GFAP) polyclonal antibody, rabbit-anti-human neuro-specific enolase polyclonal antibody and mouse-anti-human microtubal associated protein 2 (MAP-2) polyclonal antibody were provided by Wuhan Boster Company. METHODS: The experiment was carried out in the Central Laboratory of North China Coal Medical College from October 2004 to June 2005. hADASC was cultured with HCAM and its growth and morphological changes were observed under inverted phase contrast microscope. Immunocytochemistry, immunofluorescence and Western blotting were used to evaluate the expressions of Nestin, which was a specific sign of nerve precursor, neuro-specific enolase and MAP-2, which was a specific sign of nerve cell, and GFAP, which was a specific sign of neuroglial cells. MAIN OUTCOME MEASURES: Nestin, which was a specific sign of nerve precursor, neuro-specific enolase and MAP-2, which was a specific sign of nerve cell, and GFAP, which was a specific sign of neuroglial cells. RESULTS: On the 3rd day of culture, partial hADASC started deformation from slender shuttle-shape cells to neuron-like cells. It suggested that cells stretched out apophysis, which were mainly double-pole or multiple-pole cells. Five days later, immunohistochemical detection suggested that expression of Nestin (10.5±0.037) was found out in cells; meanwhile, expressions of GFAP (38.4±0.052) and neuro-specific enolase (NSE) (15.7±0.023) were also found out in cells; however, expression of MAP-2 was not observed. Western blot indicated that, 5 days after effect of HCAM, Nestin was found out in hADASC; meanwhile, expressions of GFAP and neuro-specific enolase were also found out; however, expression of MAP-2 was not observed. CONCLUSION: HCAM can induce the differentiation from hADASC to neuron-like cells in vitro.

Adipose-derived mesenchymal stromal/stem cells: An update on their phenotype in vivo and in vitro

Adipose tissue is a rich, ubiquitous and easily acces-sible source for multipotent stromal/stem cells and has, therefore, several advantages compared to other sourc-es of mesenchymal stromal/stem cells. Several studies have tried to identify the origin of the stromal/stem cell population within adipose tissue in situ. This is a complicated attempt because no marker has currently been described which unambiguously identifies native adipose-derived stromal/stem cells(ASCs). Isolated and cultured ASCs are a non-uniform preparation consisting of several subsets of stem and precursor cells. Cultured ASCs are characterized by their expression of a panel of markers(and the absence of others), whereas their in vitro phenotype is dynamic. Some markers were ex-pressed de novo during culture, the expression of some markers is lost. For a long time, CD34 expression was solely used to characterize haematopoietic stem and progenitor cells, but now it has become evident that it is also a potential marker to identify an ASC subpopula-tion in situ and after a short culture time. Nevertheless, long-term cultured ASCs do not express CD34, perhaps due to the artificial environment. This review gives an update of the recently published data on the origin and phenotype of ASCs both in vivo and in vitro. In addition, the composition of ASCs(or their subpopula-tions) seems to vary between different laboratories andpreparations. This heterogeneity of ASC preparationsmay result from different reasons. One of the main problems in comparing results from different laborato-ries is the lack of a standardized isolation and culture protocol for ASCs. Since many aspects of ASCs, suchas the differential potential or the current use in clinical trials, are fully described in other recent reviews, this review further updates the more basic research issues concerning ASCs' subpopulations, heterogeneity andculture standardization.

Ultrastructure of neuronal-like cells differentiated from adult adipose-derived stromal cells

β-mercaptoethanol induces in vitro adult adipose-derived stromal cells （ADSCs） to differentiate into neurons. However, the ultrastructural features of the differentiated neuronal-like cells remain unknown. In the present study, inverted phase contrast microscopy was utilized to observe β-mercaptoethanol-induced differentiation of neuronal-like cells from human ADSCs, and immunocytochemistry and real-time polymerase chain reaction were employed to detect expression of a neural stem cells marker （nestin）, a neuronal marker （neuron-specific enolase）, and a glial marker （glial fibrillary acidic protein）. In addition, ultrastructure of neuronal-like cells was observed by transmission election microscopy. Results revealed highest expression rate of nestin and neuron-specific enolase at 3 and 5 hours following induced differentiation; cells in the 5-hour induction group exhibited a neuronal-specific structure, i.e., Nissl bodies. However, when induction solution was replaced by complete culture medium after 8-hour induction, the differentiated cells reverted to the fibroblast-like morphology from day 1. These results demonstrate that β-mercaptoethanol-induced ADSCs induced differentiation into neural stem cells, followed by morphology of neuronal-like cells. However, this differentiation state was not stable.

Adipose-derived stromal/stem cells from different adipose depots in obesity development

The increasing prevalence of obesity is alarming because it is a risk factor for cardiovascular and metabolic diseases(such as type 2 diabetes). The occurrence of these comorbidities in obese patients can arise from white adipose tissue(WAT) dysfunctions, which affect metabolism, insulin sensitivity and promote local and systemic inflammation. In mammals, WAT depots at different anatomical locations(subcutaneous, preperitoneal and visceral) are highly heterogeneous in their morpho-phenotypic profiles and contribute differently to homeostasis and obesity development, depending on their ability to trigger and modulate WAT inflammation. This heterogeneity is likely due to the differential behavior of cells from each depot. Numerous studies suggest that adiposederived stem/stromal cells(ASC; referred to as adipose progenitor cells, in vivo)with depot-specific gene expression profiles and adipogenic and immunomodulatory potentials are keys for the establishment of the morphofunctional heterogeneity between WAT depots, as well as for the development of depot-specific responses to metabolic challenges. In this review, we discuss depot-specific ASC properties and how they can contribute to the pathophysiology of obesity and metabolic disorders, to provide guidance for researchers and clinicians in the development of ASC-based therapeutic approaches.

Isolation and identification of adipose-derived stromal/stem cells from breast cancer patients after exposure neoadjuvant chemotherapy

BACKGROUND With recent research advances,adipose-derived stromal/stem cells(ASCs)have been demonstrated to facilitate the survival of fat grafts and thus are increasingly used for reconstructive procedures following surgery for breast cancer.Unfortunately,in patients,following radiation and chemotherapy for breast cancer suggest that these cancer treatment therapies may limit stem cell cellular functions important for soft tissue wound healing.For clinical translation to patients that have undergone cancer treatment,it is necessary to understand the effects of these therapies on the ASC's ability to improve fat graft survival in clinical practice.AIM To investigate whether the impact on ASCs function capacity and recovery in cancer patients may be due to the chemotherapy.METHODS ASCs were isolated from the cancerous side and noncancerous side of the breast from the same patients with receiving neoadjuvant chemotherapy(NAC)or notreceiving NAC.ASCs were in vitro treated with 5-fluorouracil(5-FU),doxorubicin(DXR),and cyclophosphamide(Cytoxan)at various concentrations.The stem cells yield,cell viability,and proliferation rates were measured by growth curves and MTT assays.Differentiation capacity for adipogenesis was determined by qPCR analysis of the specific gene markers and histological staining.RESULTS No significant differences were observed between the yield of ASCs in patients receiving NAC treatment and not-receiving NAC.ASCs yield from the cancerous side of the breast showed lower than the noncancerous side of the breast in both patients receiving NAC and not-receiving NAC.The proliferation rates of ASCs from patients didn’t differ much before and after NAC upon in vitro culture,and these cells appeared to retain the capacity to acquire adipocyte traits simile to the ASCs from patients not-receiving NAC.After cessation and washout of the drugs for another a week of culturing,ASCs showed a slow recovery of cell growth capacity in 5-FU-treated groups but was not observed in ASCs treated with DXR groups.CONCLUSION Neoadjuvant therapies do not affect the functioning capacity of ASCs.ASCs may hold great potential to serve as a cell source for fat grafting and reconstruction in patients undergoing chemotherapy.

Cartilage and bone tissue engineering using adipose stromal/stem cells spheroids as building blocks

Scaffold-free techniques in the developmental tissue engineering area are designed to mimic in vivo embryonic processes with the aim of biofabricating,in vitro,tissues with more authentic properties.Cell clusters called spheroids are the basis for scaffold-free tissue engineering.In this review,we explore the use of spheroids from adult mesenchymal stem/stromal cells as a model in the developmental engineering area in order to mimic the developmental stages of cartilage and bone tissues.Spheroids from adult mesenchymal stromal/stem cells lineages recapitulate crucial events in bone and cartilage formation during embryogenesis,and are capable of spontaneously fusing to other spheroids,making them ideal building blocks for bone and cartilage tissue engineering.Here,we discuss data from ours and other labs on the use of adipose stromal/stem cell spheroids in chondrogenesis and osteogenesis in vitro.Overall,recent studies support the notion that spheroids are ideal"building blocks"for tissue engineering by“bottom-up”approaches,which are based on tissue assembly by advanced techniques such as three-dimensional bioprinting.Further studies on the cellular and molecular mechanisms that orchestrate spheroid fusion are now crucial to support continued development of bottom-up tissue engineering approaches such as three-dimensional bioprinting.

Intravenous administration of adipose-derived stromal cells does not ameliorate bleomycin-induced lung injury in rats

Background: Mesenchymal stromal cells (MSCs) have been studied intensively in regenerative medicine. Among MSCs, adipose tissue-derived stromal cells (ASCs) are relatively easy to obtain from a patient. Since ASCs are ideal candidates for use in the treatment of disease states including pulmonary fibrosis, we investigated whether intravenous injection of ASCs could exert a therapeutic effect against bleomycin-induced lung injury in rats. Methods: Rats were intratracheally administered bleomycin, and one week later ASCs were isolated and cultured. Two weeks after bleomycin treatment ASCs or PBS (phosphate-buffered saline) were injected to the rats. Three or six weeks after bleomycin instillation, the total cell counts and their profile in bronchoalveolar lavage fluid (BALF) were measured, and a histological evaluation was semi-quantitatively assessed for the injured lungs, followed by cell tracing. Results: The BALF cell counts and its profiles were not significantly different in the ASCs and PBS groups. Furthermore, ASC treatment led to no significant histological effect compared with the PBS treatment. Using a fluorescent cell tracer, it was noted that the ASCs homed to the injured lung areas, but some ASCs accumulated around scars, and scarcely migrated into the fibrotic areas. Conclusions: In the present study, the intravenous administration of ASCs could not reduce the severity of bleomycin-induced lung injury in a rat model. Although the ASC counts and passage numbers were suitable, the older age and fibrotic disease stage of the rats were likely responsible for the treatment failure.

Anti-osteoarthritis effect of a combination treatment with human adipose tissue-derived mesenchymal stem cells and thrombospondin 2 in rabbits

BACKGROUND Osteoarthritis(OA),a chronic age-related disease characterized by the slowly progressive destruction of articular cartilage,is one of the leading causes of disability.As a new strategy for treatment of OA,mesenchymal stem cells(MSCs)have the potential for articular cartilage regeneration.Meanwhile,thrombospondin 2(TSP2)promotes the chondrogenic differentiation of MSCs.AIM To investigate whether TSP2 induces chondrogenic differentiation of human adipose-derived MSCs(hADMSCs)and potentiates the therapeutic effects of hADMSCs in OA rabbits.METHODS We investigated the chondrogenic potential of TSP2 in hADMSCs by analyzing the expression of chondrogenic markers as well as NOTCH signaling genes in normal and TSP2 small interfering RNA(siRNA)-treated stem cells.Anterior cruciate ligament transection surgery was performed in male New Zealand white rabbits,and 8 wk later,hADMSCs(1.7×10^6 or 1.7×10^7 cells)were injected into the injured knees alone or in combination with intra-articular injection of TSP2(100 ng/knee)at 2-d intervals.OA progression was monitored by gross,radiological,and histological examinations.RESULTS In hADMSC culture,treatment with TSP2 increased the expression of chondrogenic markers(SOX9 and collagen Ⅱ)as well as NOTCH signaling genes(JAGGED1 and NOTCH3),which were inhibited by TSP2 siRNA treatment.In vivo,OA rabbits treated with hADMSCs or TSP2 alone exhibited lower degree of cartilage degeneration,osteophyte formation,and extracellular matrix loss 8 wk after cell transplantation.Notably,such cartilage damage was further alleviated by the combination of hADMSCs and TSP2.In addition,synovial inflammatory cytokines,especially tumor-necrosis factor-α,markedly decreased following the combination treatment.CONCLUSION The results indicate that TSP2 enhances chondrogenic differentiation of hADMSCs via JAGGED1/NOTCH3 signaling,and that combination therapy with hADMSCs and TSP2 exerts synergistic effects in the cartilage regeneration of OA joints.

Ameliorative effects of human adipose tissue-derived mesenchymal stem cells on myelin basic protein-induced experimental autoimmune encephalomyelitis in Lewis rats

Mesenchymal stem cells have been previously shown to exert an immunomodulatory function. The present study sought to investigate the effects of multipotential human adipose tissue-derived mesenchymal stem cells （hAdMSCs） on disease progression and cytokine expression in Lewis rats with experimental autoimmune encephalomyelitis （EAE） induced by myelin basic protein. The duration of EAE paralysis in the group treated on day 7 posfimmunization with 5 × 10^6 hAdMSCs was significantly reduced compared with the vehicle-treated controls and the 1 x 106 hAdMSC- treated group. The duration of EAE paralysis in the groups treated with 5 × 10^6 hAdMSCs on both day 1 and day 7 postimmunization was significantly reduced compared with the vehicle-treated controls and the groups treated with 5 × 10^6 hAdMSCs on both day 7 and day 10 postimmunization. The mRNA expression of interleukin-10 and indoleamine 2, 3-dioxygenase was significantly decreased in the hAdMSC-treated group compared with the vehicle-treated group. These findings suggest that the ameliorative effects of hAdMSCs on EAE symptoms operate in a dose- and time-dependent manner and can be mediated in part by the ample production of anti-inflammatory cytokines.

A familiar stranger:CD34 expression and putative functions in SVF cells of adipose tissue

Human adipose tissue obtained by liposuction is easily accessible and an abundant potential source of autologous cells for regenerative medicine applications. After digestion of the tissue and removal of differentiated adipocytes, the so-called stromal vascular fraction (SVF) of adipose, a mix of various cell types, is obtained. SVF contains mesenchymal fibroblastic cells, able to adhere to culture plastic and to generate large colonies in vitro , that closely resemble bone marrow-derived colony forming units-fibroblastic, and whose expanded progeny, adipose mesenchymal stem/stromal cells (ASC), show strong similarities with bone marrow mesenchymal stem cells. The sialomucin CD34, which is well known as a hematopoietic stem cell marker, is also expressed by ASC in native adipose tissue but its expression is gradually lost upon standard ASC expansion in vitro . Surprisingly little is known about the functional role of CD34 in the biology and tissue forming capacity of SVF cells and ASC. The present editorial provides a short introduction to the CD34 family of sialomucins and reviews the data from the literature concerning ex- pression and function of these proteins in SVF cells and their in vitro expanded progeny.

Adipose tissue-derived progenitor cells and cancer

Recruitment of stem cells and partially differentiated progenitor cells is a process which accompanies and facilitates the progression of cancer.One of the factors complicating the clinical course of cancer is obesity,a progressively widespread medical condition resulting from overgrowth of white adipose tissue(WAT),com-monly known as white fat.The mechanisms by which obesity in uences cancer risk and progression are not completely understood.Cells of WAT secret soluble molecules(adipokines) that could stimulate tumor growth,although there is no consensus on which cell populations and which adipokines are important.Recent reports suggest that WAT-derived mesenchymal stem(stromal) cells,termed adipose stem cells(ASC),may represent a cell population linking obesity and cancer.Studies in animal models demonstrate that adipokines secreted by ASC can promote tumor growth by assisting in formation of new blood vessels,a process necessary for expansion of tumor mass.Importantly,migration of ASC from WAT to tumors has been demonstrated,indicating that the tumor microenvironment in cancer may be modulated by ASC-derived trophic factors in a paracrine rather than in an endocrine manner.Here,we review possible positive and adverse implications of progenitor cell recruitment into the diseased sites with a particular emphasis on the role in cancer progression of progenitors that are expanded in obesity.

Decellularized adipose matrix provides an inductive microenvironment for stem cells in tissue regeneration

Stem cells play a key role in tissue regeneration due to their self-renewal and multidirectional differentiation,which are continuously regulated by signals from the extracellular matrix(ECM)microenvironment.Therefore,the unique biological and physical characteristics of the ECM are important determinants of stem cell behavior.Although the acellular ECM of specific tissues and organs(such as the skin,heart,cartilage,and lung)can mimic the natural microenvironment required for stem cell differentiation,the lack of donor sources restricts their development.With the rapid development of adipose tissue engineering,decellularized adipose matrix(DAM)has attracted much attention due to its wide range of sources and good regeneration capacity.Protocols for DAM preparation involve various physical,chemical,and biological methods.Different combinations of these methods may have different impacts on the structure and composition of DAM,which in turn interfere with the growth and differentiation of stem cells.This is a narrative review about DAM.We summarize the methods for decellularizing and sterilizing adipose tissue,and the impact of these methods on the biological and physical properties of DAM.In addition,we also analyze the application of different forms of DAM with or without stem cells in tissue regeneration(such as adipose tissue),repair(such as wounds,cartilage,bone,and nerves),in vitro bionic systems,clinical trials,and other disease research.

Neuronal differentiation of adipose-derived stem cells and their transplantation for cerebral ischemia

OBJECTIVE： To review published data on the biological characteristics, differentiation and applications of adipose-derived stem cells in ischemic diseases. DATA RETRIEVAL： A computer-based online search of reports published from January 2005 to June 2012 related to the development of adipose-derived stem cells and their transplantation for treatment of cerebral ischemia was performed in Web of Science using the key words ＂adipose-derived stem cells＂, ＂neural-like cells＂, ＂transplantation＂, ＂stroke＂, and ＂cerebral ischemia＂. SELECTION CRITERIA： The documents associated with the development of adipose-derived stem cells and their transplantation for treatment of cerebral ischemia were selected, and those published in the last 3-5 years or in authoritative journals were preferred in the same field. Totally 89 articles were obtained in the initial retrieval, of which 53 were chosen based on the inclusion criteria. MAIN OUTCOME MEASURES： Biological characteristics and induced differentiation of adipose-derived stem cells and cell transplantation for disease treatment as well as the underlying mechanism of clinical application. RESULTS： The advantages of adipose-derived stem cells include their ease of procurement, wide availability, rapid expansion, low tumorigenesis, low immunogenicity, and absence of ethical constraints. Preclinical experiments have demonstrated that transplanted adipose-derived stem cells can improve neurological functions, reduce small regions of cerebral infarction, promote angiogenesis, and express neuron-specific markers. The improvement of neurological functions was demonstrated in experiments using different methods and time courses of adipose-derived stem cell transplantation, but the mechanisms remain unclear. CONCLUSION： Further research into the treatment of ischemic disease by adipose-derived stem cell transplantation is needed to determine their mechanism of action.

Adipose-derived regenerative therapies for the treatment of knee osteoarthritis

Knee osteoarthritis is a degenerative condition with a significant disease burden and no disease-modifying therapy.Definitive treatment ultimately requires joint replacement.Therapies capable of regenerating cartilage could significantly reduce financial and clinical costs.The regenerative potential of mesenchymal stromal cells(MSCs)has been extensively studied in the context of knee osteoarthritis.This has yielded promising results in human studies,and is likely a product of immunomodulatory and chondroprotective biomolecules produced by MSCs in response to inflammation.Adipose-derived MSCs(ASCs)are becoming increasingly popular owing to their relative ease of isolation and high proliferative capacity.Stromal vascular fraction(SVF)and micro-fragmented adipose tissue(MFAT)are produced by the enzymatic and mechanical disruption of adipose tissue,respectively.This avoids expansion of isolated ASCs ex vivo and their composition of heterogeneous cell populations,including immune cells,may potentiate the reparative function of ASCs.In this editorial,we comment on a multicenter randomized trial regarding the efficacy of MFAT in treating knee osteoarthritis.We discuss the study’s findings in the context of emerging evidence regarding adipose-derived regenerative therapies.An underlying mechanism of action of ASCs is proposed while drawing important distinctions between the properties of isolated ASCs,SVF,and MFAT.

New frontiers in scar management:Adipose tissue transplantation techniques

A scar is a condition characterized by excessive repair of skin tissue,resulting in a fibroproliferative disorder marked by abnormal deposition of extracellular matrix.This disorder typically stems from deep dermal damage caused by burns or trauma and presents with symptoms such as itching and pain.Moreover,scarring can lead to disfigurement and psychological distress in affected individuals,making it a prevalent concern in burn plastic surgery outpatient clinics.In the current scar treatment landscape,one of the forefront approaches involves the grafting of adipose tissue and its components.This cutting-edge methodology encompasses various techniques,including nanofat grafting,adipose-derived stem cell matrigel applications,stromal vascular component transplantation,and adipose-derived mesenchymal stem cell infusion.Research in this domain has consistently demonstrated the remarkable capabilities of adipose tissue and its components in tissue regeneration,extracellular matrix remodeling,and anti-fibrotic actions.Notably,topical grafting of adipose tissue has emerged as a promising therapeutic avenue,showing significant improvements in both visual appearance and symptomatic relief associated with scars.The multifaceted functions of adipose tissue play a pivotal role in enhancing the overall outcomes of scar treatments.Therefore,this review aims to comprehensively evaluate and highlight the role of adipose tissue and its various components in scar treatment.By providing a theoretical foundation,this review aimed to serve as a valuable reference for improving the efficacy of scar management strategies.

Adipose stromal/stem cells in regenerative medicine:Potentials and limitations

This article presents the stem and progenitor cells from subcutaneous adipose tissue,briefly comparing them with their bone marrow counterparts,and discussing their potential for use in regenerative medicine.Subcutaneous adipose tissue differs from other mesenchymal stromal/stem cells(MSCs)sources in that it contains a pre-adipocyte population that dwells in the adventitia of robust blood vessels.Pre-adipocytes are present both in the stromal-vascular fraction(SVF;freshly isolated cells)and in the adherent fraction of adipose stromal/stem cells(ASCs;in vitro expanded cells),and have an active role on the chronic inflammation environment established in obesity,likely due their monocyticmacrophage lineage identity.The SVF and ASCs have been explored in cell therapy protocols with relative success,given their paracrine and immunomodulatory effects.Importantly,the widely explored multipotentiality of ASCs has direct application in bone,cartilage and adipose tissue engineering.The aim of this editorial is to reinforce the peculiarities of the stem and progenitor cells from subcutaneous adipose tissue,revealing the spheroids as a recently described biotechnological tool for cell therapy and tissue engineering.Innovative cell culture techniques,in particular 3D scaffold-free cultures such as spheroids,are now available to increase the potential for regeneration and differentiation of mesenchymal lineages.Spheroids are being explored not only as a model for cell differentiation,but also as powerful 3D cell culture tools to maintain the stemness and expand the regenerative and differentiation capacities of mesenchymal cell lineages.

Adipose tissue in bone regeneration-stem cell source and beyond

Adipose tissue(AT)is recognized as a complex organ involved in major homeostatic body functions,such as food intake,energy balance,immunomodulation,development and growth,and functioning of the reproductive organs.The role of AT in tissue and organ homeostasis,repair and regeneration is increasingly recognized.Different AT compartments(white AT,brown AT and bone marrow AT)and their interrelation with bone metabolism will be presented.AT-derived stem cell populations-adipose-derived mesenchymal stem cells and pluripotentlike stem cells.Multilineage differentiating stress-enduring and dedifferentiated fat cells can be obtained in relatively high quantities compared to other sources.Their role in different strategies of bone and fracture healing tissue engineering and cell therapy will be described.The current use of AT-or AT-derived stem cell populations for fracture healing and bone regenerative strategies will be presented,as well as major challenges in furthering bone regenerative strategies to clinical settings.

Human adipose tissue contains erythroid progenitors expressing fetal hemoglobin

AIM: To investigate the origin of hematopoietic progenitors contained in the stromal vascular fraction(SVF)of human adipose tissue.METHODS: Tissue samples obtained from lipectomies were subjected to enzymatic digestion with collagenase to obtain a single-cell suspension. The centrifuged cell pellet, termed SVF, was separated immunomagnetically into CD45+and CD45-cells and cultured in serum-free medium containing hematopoietic cytokines. The freshly isolated and cultured cells were evaluated to determine their ability to form hematopoietic colony-forming units in clonogenic assays and for the expression of certain hematopoietic transcription factors by reversetranscription-polymerase chain reaction; the gene expression level was compared to that in CD34+hematopoietic progenitor cells from cord blood(CB) and adult peripheral blood(PB). To characterize erythroid progenitors, burst-forming units-erythroid(BFU-E) were developed in a semisolid medium under different culture conditions, and the hemoglobin composition and globin gene expression in the erythroid colonies were determined.RESULTS: The transcription factors SCL/TAL1, RUNX1,RUNX2 and GATA2 were expressed in both the CD45+and CD45-SVF populations; however, in contrast to our observations in the CD34+cells from CB and adult PB, GATA1 was not detected. Nevertheless, GATA1could be detected in the SVF cells after seven days in culture, whereas its expression was upregulated in the CB CD34+cells. The analysis of BFU-E-derived colonies revealed that virtually all erythroid cells produced by SVF cells expressed fetal hemoglobin, and the γ-globin mRNA levels ranged between those obtained in the adult- and neonatal-derived erythroid cells. Moreover,the SVF-derived erythroid cells synthesized similar levels of α- and β-globin mRNA, whereas the α-globin transcript levels were consistently higher those ofβ-globin in the cells derived from CB or PB CD34+cells. Furthermore, although the cellular distribution of hemoglobin in the erythroid cells derived from the CD34+cells obtained from hematopoietic tissues was dependent on the presence or absence of serum in the culture medium, this did not affect the SVF-derived erythroid cells.CONCLUSION: Our results demonstrate that hematopoietic progenitors in SVF have molecular and functional features that differ from those exhibited by circulating progenitors, suggesting the possibility of a different origin.