Emerging strategies for nerve repair and regeneration in ischemic stroke:neural stem cell therapy

Ischemic stroke is a major cause of mortality and disability worldwide,with limited treatment options available in clinical practice.The emergence of stem cell therapy has provided new hope to the field of stroke treatment via the restoration of brain neuron function.Exogenous neural stem cells are beneficial not only in cell replacement but also through the bystander effect.Neural stem cells regulate multiple physiological responses,including nerve repair,endogenous regeneration,immune function,and blood-brain barrier permeability,through the secretion of bioactive substances,including extracellular vesicles/exosomes.However,due to the complex microenvironment of ischemic cerebrovascular events and the low survival rate of neural stem cells following transplantation,limitations in the treatment effect remain unresolved.In this paper,we provide a detailed summary of the potential mechanisms of neural stem cell therapy for the treatment of ischemic stroke,review current neural stem cell therapeutic strategies and clinical trial results,and summarize the latest advancements in neural stem cell engineering to improve the survival rate of neural stem cells.We hope that this review could help provide insight into the therapeutic potential of neural stem cells and guide future scientific endeavors on neural stem cells.

Evaluation of genetic response of mesenchymal stem cells to nanosecond pulsed electric fields by whole transcriptome sequencing

BACKGROUND Mesenchymal stem cells(MSCs)modulated by various exogenous signals have been applied extensively in regenerative medicine research.Notably,nanosecond pulsed electric fields(nsPEFs),characterized by short duration and high strength,significantly influence cell phenotypes and regulate MSCs differentiation via multiple pathways.Consequently,we used transcriptomics to study changes in messenger RNA(mRNA),long noncoding RNA(lncRNA),microRNA(miRNA),and circular RNA expression during nsPEFs application.AIM To explore gene expression profiles and potential transcriptional regulatory mechanisms in MSCs pretreated with nsPEFs.METHODS The impact of nsPEFs on the MSCs transcriptome was investigated through whole transcriptome sequencing.MSCs were pretreated with 5-pulse nsPEFs(100 ns at 10 kV/cm,1 Hz),followed by total RNA isolation.Each transcript was normalized by fragments per kilobase per million.Fold change and difference significance were applied to screen the differentially expressed genes(DEGs).Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to elucidate gene functions,complemented by quantitative polymerase chain reaction verification.RESULTS In total,263 DEGs were discovered,with 92 upregulated and 171 downregulated.DEGs were predominantly enriched in epithelial cell proliferation,osteoblast differentiation,mesenchymal cell differentiation,nuclear division,and wound healing.Regarding cellular components,DEGs are primarily involved in condensed chromosome,chromosomal region,actin cytoskeleton,and kinetochore.From aspect of molecular functions,DEGs are mainly involved in glycosaminoglycan binding,integrin binding,nuclear steroid receptor activity,cytoskeletal motor activity,and steroid binding.Quantitative real-time polymerase chain reaction confirmed targeted transcript regulation.CONCLUSION Our systematic investigation of the wide-ranging transcriptional pattern modulated by nsPEFs revealed the differential expression of 263 mRNAs,2 miRNAs,and 65 lncRNAs.Our study demonstrates that nsPEFs may affect stem cells through several signaling pathways,which are involved in vesicular transport,calcium ion transport,cytoskeleton,and cell differentiation.

Mesenchymal Stem Cells and Tooth Engineering

Tooth loss compromises human oral health. Although several prosthetic methods, such as artificial denture and dental implants, are clinical therapies to tooth loss problems, they are thought to have safety and usage time issues. Recently, tooth tissue engineering has attracted more and more attention. Stem cell based tissue engineering is thought to be a promising way to replace the missing tooth. Mesenchymal stem cells （MSCs） are multipotent stem cells which can differentiate into a variety of cell types. The potential MSCs for tooth regeneration mainly include stem cells from human exfoliated deciduous teeth （SHEDs）, adult dental pulp stem cells （DPSCs）, stem cells from the apical part of the papilla （SCAPs）, stem cells from the dental follicle （DFSCs）, periodontal ligament stem cells （PDLSCs） and bone marrow derived mesenchymal stem cells （BMSCs）. This review outlines the recent progress in the mesenchymal stem cells used in tooth regeneration.

Bone tissue engineering via nanostructured calcium phosphate biomaterials and stem cells

Tissue engineering is promising to meet the increasing need for bone regeneration. Nanostructured calcium phosphate （CAP） biomaterials/scaffolds are of special interest as they share chemical/crystallographic similarities to inorganic components of bone. Three applications of nano-CaP are discussed in this review： nanostructured calcium phosphate cement （CPC）; nano-CaP composites; and nano-CaP coatings. The interactions between stem cells and nano-CaP are highlighted, including cell attachment, orientation/ morphology, differentiation and in vivo bone regeneration. Several trends can be seen： （i） nano-CaP biomaterials support stem cell attachment/proliferation and induce osteogenic differentiation, in some cases even without osteogenic supplements; （ii） the influence of nano-CaP surface patterns on cell alignment is not prominent due to non-uniform distribution of nano-crystals; （iii） nano-CaP can achieve better bone regeneration than conventional CaP biomaterials; （iv） combining stem cells with nano-CaP accelerates bone regeneration, the effect of which can be further enhanced by growth factors; and （v） cell microencapsulation in nano-CaP scaffolds is promising for bone tissue engineering. These understandings would help researchers to further uncover the underlying mechanisms and interactions in nano-CaP stem cell constructs in vitro and in vivo, tailor nano-CaP composite construct design and stem cell type selection to enhance cell function and bone regeneration, and translate laboratory findings to clinical treatments.

Application of platelet-rich plasma with stem cells in bone and periodontal tissue engineering

Presently, there is a high paucity of bone grafts in the United States and worldwide. Regenerating bone is of prime concern due to the current demand of bone grafts and the increasing number of diseases causing bone loss. Autogenous bone is the present gold standard of bone regeneration. However, disadvantages like donor site morbidity and its decreased availability limit its use. Even allografts and synthetic grafting materials have their own limitations. As certain specific stem cells can be directed to differentiate into an osteoblastic lineage in the presence of growth factors(GFs), it makes stem cells the ideal agents for bone regeneration.Furthermore, platelet-rich plasma(PRP), which can be easily isolated from whole blood, is often used for bone regeneration, wound healing and bone defect repair. When stem cells are combined with PRP in the presence of GFs, they are able to promote osteogenesis. This review provides in-depth knowledge regarding the use of stem cells and PRP in vitro, in vivo and their application in clinical studies in the future.

Potential of dental pulp stem cells and their products in promoting peripheral nerve regeneration and their future applications

Peripheral nerve injury(PNI)seriously affects people’s quality of life.Stem cell therapy is considered a promising new option for the clinical treatment of PNI.Dental stem cells,particularly dental pulp stem cells(DPSCs),are adult pluripotent stem cells derived from the neuroectoderm.DPSCs have significant potential in the field of neural tissue engineering due to their numerous advantages,such as easy isolation,multidifferentiation potential,low immunogenicity,and low transplant rejection rate.DPSCs are extensively used in tissue engineering and regenerative medicine,including for the treatment of sciatic nerve injury,facial nerve injury,spinal cord injury,and other neurodegenerative diseases.This article reviews research related to DPSCs and their advantages in treating PNI,aiming to summarize the therapeutic potential of DPSCs for PNI and the underlying mechanisms and providing valuable guidance and a foundation for future research.

Regenerative Engineering for Knee Osteoarthritis Treatment： Biomaterials and Cell-Based Technologies

Knee osteoarthritis （OA） is the most common form of arthritis worldwide. The incidence of this disease is rising and its treatment poses an economic burden. Two early targets of knee OA treatment include the predominant symptom of pain, and cartilage damage in the knee joint. Current treatments have been beneficial in treating the disease but none is as effective as total knee arthroplasty （TKA）. However, while TKA is an end-stage solution of the disease, it is an invasive and expensive procedure, Therefore, innovative regenerative engineering strategies should be established as these could defer or annul the need for a TKA. Several biomaterial and cell-based therapies are currently in development and have shown early promise in both preclinical and clinical studies. The use of advanced biomaterials and stem cells independently or in conjunction to treat knee OA could potentially reduce pain and regenerate fo- cal articular cartilage damage. In this review, we discuss the pathogenesis of pain and cartilage damage in knee OA and explore novel treatment options currently being studied, along with some of their limitations.

Liver regeneration using decellularized splenic scaffold: a novel approach in tissue engineering

BACKGROUND： The potential application of decellularized liver scaffold for liver regeneration is limited by severe shortage of donor organs. Attempt of using heterograft scaffold is accompanied with high risks of zoonosis and immunological rejection. We proposed that the spleen, which procured more extensively than the liver, could be an ideal source of decellularized scaffold for liver regeneration. METHODS： After harvested from donor rat, the spleen was processed by 12-hour freezing/thawing ×2 cycles, then circulation perfusion of 0.02% trypsin and 3% Triton X-100 sequentially through the splenic artery for 32 hours in total to prepare decellularized scaffold. The structure and component characteristics of the scaffold were determined by hematoxylin and eosin and immumohistochemical staining, scanning electron microscope, DNA detection, porosity measurement, biocompatibility and cytocompatibility test. Recellularization of scaffold by 5×106 bone marrow mesenchymal stem cells（BMSCs） was carried out to preliminarily evaluate the feasibility of liver regeneration by BMSCs reseeding and differentiation in decellularized splenic scaffold.RESULTS： After decellularization, a translucent scaffold, which retained the gross shape of the spleen, was generated. Histological evaluation and residual DNA quantitation revealed the remaining of extracellular matrix without nucleus and cytoplasm residue. Immunohistochemical study proved the existence of collagens I, IV, fibronectin, laminin and elastin in decellularized splenic scaffold, which showed a similarity with decellularized liver. A scanning electron microscope presented the remaining three-dimensional porous structure of extracellular matrix and small blood vessels. The poros-ity of scaffold, aperture of 45.36±4.87 μm and pore rate of 80.14%±2.99% was suitable for cell engraftment. Subcutaneous implantation of decellularized scaffold presented good histocompatibility, and recellularization of the splenic scaffold demonstrated that BMSCs could locate and survive in the decellularized matrix. CONCLUSION： Considering the more extensive organ source and satisfying biocompatibility, the present study indicated that the three-dimensional decellularized splenic scaffold might have considerable potential for liver regeneration when combined with BMSCs reseeding and differentiation.

Tethering of Gly-Arg-Gly-Asp-Ser-Pro-Lys Peptides on Mg-Doped Hydroxyapatite

Stem cell homing, namely the recruitment of mesenchymal stem cells （MSCs） to injured tissues, is highly effective for bone regeneration in vivo. In order to explore whether the incorporation of mimetic peptide sequences on magnesium-doped （Mg-doped） hydroxyapatite （HA） may regulate the homing of MSCs, and thus induce cell migration to a specific site, we covalently functionalized MgHA disks with two chemotactic/haptotactic factors： either the fibronectin fragment III1-C human （FF III1-C）, or the peptide sequence Gly-Arg-Gly-Asp-Ser-Pro-Lys, a fibronectin analog that is able to bind to integrin trans- membrane receptors. Preliminary biological evaluation of MSC viability, analyzed by 3-（4,5-dimethyl- thiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） test, suggested that stem cells migrate to the MgHA disks in resoonse to the grafted haototaxis stimuli.