Dental Pulp Stem Cells: A Promising Tool for Bone Regeneration

Human tissues are different in term of regenerative properties. Stem cells are a promising tool for tissue regeneration, thanks to their particular characteristics of proliferation, differentiation and plasticity. Several “loci” or “niches” within the adult human body are colonized by a significant number of stem cells. However, access to these potential collection sites often is a limiting point. The interaction with biomaterials is a further point that needs to be considered for the therapeutic use of stem cells. Dental pulp stem cells (DPSCs) have been demonstrated to answer all of these issues: access to the collection site of these cells is easy and produces very low morbidity; extraction of stem cells from pulp tissue is highly efficiency; they have an extensive differentiation ability; and the demonstrated interactivity with biomaterials makes them ideal for tissue reconstruction. SBP-DPSCs are a multipotent stem cell subpopulation of DPSCs which are able to differentiate into osteoblasts, synthesizing 3D woven bone tissue chips in vitro and that are capable to synergically differentiate into osteoblasts and endotheliocytes. Several studied have been performed on DPSCs and they mainly found that these cells are multipotent stromal cells that can be safety cryopreserved, used with several scaffolds, that can extensively proliferate, have a long lifespan and build in vivo an adult bone with Havers channels and an appropriate vascularization. A definitive proof of their ability to produce dentin has not been yet done. Interestingly, they seem to possess immunoprivileges as they can be grafted into allogenic tissues and seem to exert anti-inflammatory abilities, like many other mesenchymal stem cells. The easy management of dental pulp stem cells make them feasible for use in clinical trials on human patients. An erratum to this article can be found at     

Mesenchymal Stem/Progenitor Cells Derived from Articular Cartilage,Synovial Membrane and Synovial Fluid for Cartilage Regeneration: Current Status and Future Perspectives

Large articular cartilage defects remain an immense challenge in the field of regenerative medicine because of their poor intrinsic repair capacity. Currently, the available medical interventions can relieve clinical symptoms to some extent, but fail to repair the cartilaginous injuries with authentic hyaline cartilage. There has been a surge of interest in developing cell-based therapies, focused particularly on the use of mesenchymal stem/progenitor cells with or without scaffolds. Mesenchymal stem/progenitor cells are promising graft cells for tissue regeneration, but the most suitable source of cells for cartilage repair remains controversial. The tissue origin of mesenchymal stem/progenitor cells notably influences the biological properties and therapeutic potential. It is well known that mesenchymal stem/progenitor cells derived from synovial joint tissues exhibit superior chondrogenic ability compared with those derived from non-joint tissues; thus, these cell populations are considered ideal sources for cartilage regeneration. In addition to the progress in research and promising preclinical results, many important research questions must be answered before widespread success in cartilage regeneration is achieved. This review outlines the biology of stem/progenitor cells derived from the articular cartilage, the synovial membrane, and the synovial fluid, including their tissue distribution, function and biological characteristics. Furthermore, preclinical and clinical trials focusing on their applications for cartilage regeneration are summarized, and future research perspectives are discussed.     

Effect of Human Parathyroid Hormone on Hematopoietic Progenitor Cells in NOD/SCID Mice Co-Transplanted with Human Cord Blood Mononuclear Cells and Mesenchymal Stem Cells

Purpose

We evaluated the effect of human parathyroid hormone (hPTH) on the engraftment and/or in vivo expansion of hematopoietic stem cells in an umbilical cord blood (UCB)-xenotransplantation model. In addition, we assessed its effect on the expression of cell adhesion molecules.

Materials and Methods

Female NOD/SCID mice received sublethal total body irradiation with a single dose of 250 cGy. Eighteen to 24 hours after irradiation, 1×10⁷ human UCB-derived mononuclear cells (MNCs) and 5×10⁶ human UCB-derived mesenchymal stem cells (MSCs) were infused via the tail vein. Mice were randomly divided into three groups: Group 1 mice received MNCs only, Group 2 received MNCs only and were then treated with hPTH, Group 3 mice received MNCs and MSCs, and were treated with hPTH.

Results

Engraftment was achieved in all the mice. Bone marrow cellularity was approximately 20% in Group 1, but 70-80% in the hPTH treated groups. Transplantation of MNCs together with MSCs had no additional effect on bone marrow cellularity. However, the proportion of human CD13 and CD33 myeloid progenitor cells was higher in Group 3, while the proportion of human CD34 did not differ significantly between the three groups. The proportion of CXCR4 cells in Group 3 was larger than in Groups 1 and 2 but without statistical significance.

Conclusion

We have demonstrated a positive effect of hPTH on stem cell proliferation and a possible synergistic effect of MSCs and hPTH on the proportion of human hematopoietic progenitor cells, in a xenotransplantation model. Clinical trials of the use of hPTH after stem cell transplantation should be considered.     

Mesenchymal Stem Cells for Cardiac Therapy: Practical Challenges and Potential Mechanisms

Cell based treatments for myocardial infarction have demonstrated efficacy in the laboratory and in phase I clinical trials, but the understanding of such therapies remains incomplete. Mesenchymal stem cells (MSCs) are classically defined as maintaining the ability to generate mesenchyme-derived cell types, namely adipocytes, chondrocytes and osteocytes. Recent evidence suggests these cells may in fact harbor much greater potency than originally realized, as several groups have found that MSCs can form cardiac lineage cells in vitro. Additionally, experimental coculture of MSCs with cardiomyocytes appears to improve contractile function of the latter. Bolstered by such findings, several clinical trials have begun to test MSC transplantation for improving post-infarct cardiac function in human patients. The results of these trials have been mixed, underscoring the need to develop a deeper understanding of the underlying stem cell biology. To help synthesize the breadth of studies on the topic, this paper discusses current challenges in the field of MSC cellular therapies for cardiac repair, including methods of cell delivery and the identification of molecular markers that accurately specify the therapeutically relevant mesenchymal cell types. The various possible mechanisms of MSC mediated cardiac improvement, including somatic reprogramming, transdifferentiation, paracrine signaling, and direct electrophysiological coupling are also reviewed. Finally, we consider the traditional cell culture microenvironment, and the promise of cardiac tissue engineering to provide biomimetic in vitro model systems to more faithfully investigate MSC biology, helping to safely and effectively translate exciting discoveries in the laboratory to meaningful therapies in the clinic.     

Differentiation of Stem Cells into Insulin-Producing Cells: Current Status and Challenges

Diabetes mellitus is one of the most serious public health challenges of the twenty-first century. Allogenic islet transplantation is an efficient therapy for type 1 diabetes. However, immune rejection, side effects of immunosuppressive treatment as well as lack of sufficient donor organs limits its potential. In recent years, several promising approaches for generation of new pancreatic β cells have been developed. This review provides an overview of current status of pancreatic and extra-pancreatic stem cells differentiation into insulin-producing cells and the possible application of these cells for diabetes treatment. The PubMed database was searched for English language articles published between 2001 and 2012, using the keyword combinations: diabetes mellitus, differentiation, insulin-producing cells, stem cells.     

Stem Cells in Liver Regeneration and Their Potential Clinical Applications

Stem cells constitute a population of “primitive cells” with the ability to divide indefinitely and give rise to specialized cells under special conditions. Because of these two characteristics they have received particular attention in recent decades. These cells are the primarily responsible factors for the regeneration of tissues and organs and for the healing of lesions, a feature that makes them a central key in the development of cell-based medicine, called Regenerative Medicine. The idea of wound and organ repair and body regeneration is as old as the mankind, reflecting the human desire for inhibiting aging and immortality and it is first described in the ancient Greek myth of Prometheus. It is of interest that the myth refers to liver, an organ with remarkable regenerative ability after loss of mass and function caused by liver injury or surgical resection. Over the last decade there has been an important progress in understanding liver physiology and the mechanisms underlying hepatic development and regeneration. As liver transplantation, despite its difficulties, remains the only effective therapy for advanced liver disease so far, scientific interest has nowadays been orientated towards Regenerative Medicine and the use of stem cells to repair damaged liver. This review is focused on the available literature concerning the role of stem cells in liver regeneration. It summarizes the results of studies concerning endogenous liver regeneration and stem cell experimental protocols. Moreover, this review discusses the clinical studies that have been conducted in humans so far.     

Bone Tissue Engineering Using Human Mesenchymal Stem Cells: Effects of Scaffold Material and Medium Flow

We report studies of bone tissue engineering using human mesenchymal stem cells (MSCs), a protein substrate (film or scaffold; fast degrading unmodified collagen, or slowly degrading cross-linked collagen and silk), and a bioreactor (static culture, spinner flask, or perfused cartridge). MSCs were isolated from human bone marrow, characterized for the expression of cell surface markers and the ability to undergo chondrogenesis and osteogenesis in vitro, and cultured for 5 weeks. MSCs were positive for CD105/endoglin, and had a potential for chondrogenic and osteogenic differentiation. In static culture, calcium deposition was similar for MSC grown on collagen scaffolds and films. Under medium flow, MSC on collagen scaffolds deposited more calcium and had a higher alcaline phosphatase (AP) activity than MSC on collagen films. The amounts of DNA were markedly higher in constructs based on slowly degrading (modified collagen and silk) scaffolds than on fast degrading (unmodified collagen) scaffolds. In spinner flasks, medium flow around constructs resulted in the formation of bone rods within the peripheral region, that were interconnected and perpendicular to the construct surface, whereas in perfused constructs, individual bone rods oriented in the direction of fluid flow formed throughout the construct volume. These results suggest that osteogenesis in cultured MSC can be modulated by scaffold properties and flow environment.     

碱性成纤维细胞生长因子基因转染对间充质干细胞生物学行为的调控

为探讨碱性成纤维细胞生长因子(bFGF)基因转染对间充质干细胞(MSCs)增殖、定向分化等生物学行为的调控作用，本文将体外具有促进MSCs增殖分化及毛细血管增殖等多重生物学效应的bFGF基因转入骨组织工程首选种子细胞——MSCs，通过免疫组化SABC法检测其瞬时与稳定表达，并检测转基因细胞增殖活力及碱性磷酸酶(ALP)与骨钙素(OC)合成情况。结果表明，bFGF基因能被转入MSCs并得到稳定表达，转基因细胞增殖与OC合成明显增强，ALP活性无明显变化。因此，转基因MSCs可使bFGF持续高效发挥作用，克服了使用外源性bFGF半衰期短，需反复大剂量给药的缺点；bFGF基因转染可促进MSCs增殖并调控其定向分化，使其获得良好的生物学活性；从而为把组织工程学与分子生物学有机结合，用分子组织工程学技术高质量地修复骨缺损奠定了良好的基础     

Endothelial Progenitor Cells: Current Issues on Characterization and Challenging Clinical Applications

Since their discovery about a decade ago, endothelial precursor cells (EPC) have been subjected to intensive investigation. The vision to stimulate respectively suppress a key player of vasculogenesis opened a plethora of clinical applications. However, as research opened deeper insights into EPC biology, the enthusiasm of the pioneer era has been damped in favour of a more critical view. Recent research is focused on three major questions: The fact that the number of EPC in peripheral blood is exceedingly low has consistently raised suspicion whether these cells can plausibly have an impact on physiological or pathophysiological processes. Secondly, whereas the key role of EPC in tumourigenesis has been strongly emphasized by various groups in the past, recent publications are challenging this hypothesis. Thirdly, the lack of consensus on EPC-defining markers and standardized protocols for their detection have repeatedly led to difficulties concerning comparability between papers. In this current review, an overview on recent findings on EPC biology is given, their challenging clinical implications are discussed and the perplexity underlying the current controversial debate is illustrated.     

Regenerative Potential of Human Schneiderian Membrane: Progenitor Cells and Epithelial‐Mesenchymal Transition

An innate osteogenic potential of the Schneiderian membrane (SM) is progressively assessed in studies ranging from non‐human species to human subjects. It has relevance for endosteal placement and osseointegration. Nestin‐expressing osteogenic progenitor cells are allegedly involved in bone formation and remodelling. Nestin phenotype was not assessed previously in human SM. We therefore aimed to fill that particular gap in the literature. Bioptic samples of human adult SM were obtained during surgery from eight adult patients, operated for non‐malignant pathologies. Immunohistochemistry on paraffin‐embedded tissue samples used primary antibodies against nestin, CD45, CD146, cytokeratin 7 (CK7), and alpha‐smooth muscle actin (α‐SMA). Nestin expression was consistently found in endothelial cells, and was scarcely encountered in pericytes, putative stromal stem/progenitor cells, as well as in glandular epithelial cells. Moreover, woven bone formation in the periosteal layer of the SM can also be regarded as evidence of the osteogenic potential of this membrane. Nestin and CD45 expression in cells of the primary bone supports the osteogenic potential of SM nestin‐expressing cells and a possible involvement of hematopoietic stem cells in maxillary sinus floor remodeling. CD146, a known inducer of epithelial‐mesenchymal transition (EMT), was expressed in epithelia, as was CK7. Isolated stromal cells were found expressing CD146, CK7 and α‐SMA, suggesting that regenerative processes happening in the SM may also involve processes of EMT which generate stem/progenitor cells. This study provides additional evidence for the regenerative potential of the Schneiderian membrane and identifies potential roles for cells of its stem niche in osteogenesis. Anat Rec, 298:2132–2140, 2015. © 2015 Wiley Periodicals, Inc.     

Adipose Tissue-Derived Mesenchymal Stem Cells Facilitate Hematopoiesis in Vitro and in Vivo : Advantages Over Bone Marrow-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have emerged as a new therapeutic modality for reconstituting the hematopoietic microenvironment by improving engraftment in stem cell transplantation. However, the availability of conventional bone marrow (BM)-derived MSCs (BMSCs) is limited. Recent studies showed that a large number of MSCs can be easily isolated from fat tissue (adipose tissue-derived MSCs [ADSCs]). In this study, we extensively evaluated the hematopoiesis-supporting properties of ADSCs, which are largely unknown. In vitro coculture and progenitor assays showed that ADSCs generated significantly more granulocytes and progenitor cells from human hematopoietic stem cells (HSCs) than BMSCs. We found that ADSCs express the chemokine CXCL12, a critical regulator of hematopoiesis, at levels that are three fold higher than those with BMSCs. The addition of a CXCL12 receptor antagonist resulted in a lower yield of granulocytes from ADSC layers, whereas the addition of recombinant CXCL12 to BMSC cocultures promoted the growth of granulocytes. In vivo cell homing assays showed that ADSCs facilitated the homing of mouse HSCs to the BM better than BMSCs. ADSCs injected into the BM cavity of fatally irradiated mice reconstituted hematopoiesis more promptly than BMSCs and subsequently rescued mice that had received a low number of HSCs. Secondary transplantation experiments showed that ADSCs exerted favorable effects on long-term HSCs. These results suggest that ADSCs can be a promising therapeutic alternative to BMSCs.Hematopoiesis is a dynamic process that involves self-renewal of hematopoietic stem cells in the bone marrow, generation of lineage-committed cells, and mobilization of mature cells into the bloodstream. Mesenchymal stem cells (MSCs) present in bone marrow (BM) are thought to give rise to cells that constitute the hematopoietic microenvironment. MSCs produce a number of cytokines and extracellular matrix proteins and express cell adhesion molecules, all of which are involved in the regulation of hematopoiesis.¹ Human MSCs, when injected into the bone marrow cavity of nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice, differentiate into pericytes, myofibroblasts, BM stromal cells, bone osteocytes, bone-lining osteoblasts, and endothelial cells, which constitute the functional components of the hematopoietic microenvironment.² In recent studies, cotransplantation of human MSCs and HSCs resulted in increased chimerism or accelerated hematopoietic recovery (or both) in animal models and in humans.^3,4,5,6All of the above studies used bone marrow-derived MSCs (BMSCs). However, there are several drawbacks in the use of BMSCs for clinical application, including the fact that they are only available in limited number even though large quantities of infused cells are required for treatment. In addition, there is a possibility that BMSCs might be contaminated with malignant cells when they are harvested from patients with a hematological malignancy (eg, leukemia). The discoveries that a large number of nonadipocyte stem cells exist in fat tissue (adipose tissue-derived MSCs [ADSCs]) and that these cells can be rapidly expanded ex vivo, suggested that ADSCs might be useful for clinical applications.⁷ Recent studies showed that ADSCs are a viable alternative to BMSCs for treatment of animal models of various kinds of diseases.^8,9,10,11,12 However, it has been reported that even though ADSCs and BMSCs are very similar, ADSCs are not completely identical to BMSCs.^13,14 To date, little is known concerning the ability of ADSCs to support hematopoiesis. We therefore extensively examined the hematopoiesis-supporting properties of ADSCs in vitro and in vivo and report that ADSCs possess several advantages over BMSCs.     

骨组织工程中人骨髓间质干细胞动态种植和静态种植的比较研究

分别采用动态种植(旋转烧瓶法)和静态种植方法种植人骨髓间质干细胞,于种植后的两周内测定细胞-载体构件中DNA含量;利用组织学光镜和扫描电镜观察细胞的分布情况;运用荧光标记RT-PCR技术测定相关成骨基因的表达。构件中DNA含量测定表明,对于静态种植,当初始种植密度为每载体400×103(8.9×104/mm3)时,DNA的含量达到最高;在此基础上提高初始种植密度,并不能进一步提高构件DNA含量。光镜和扫描电镜观察可见动态种植后人骨髓间质干细胞在载体中的分布相对均匀,静态种植后细胞在载体中出现聚集现象;荧光标记RT-PCR证明,体外构件培养两周后,动态种植后的细胞-载体构件中有较多的成骨基因表达。提示人骨髓间质干细胞的静态种植效率较低;动态种植是一种优于静态种植的可行方法。     

Nerve Fiber Regeneration in the Rat Sciatic Nerve After Injury and Administration of Mesenchymal Stem Cells

Neuroscience and Behavioral Physiology - Experimental studies seeking a means of stimulating regeneration of damaged nerve conductors frequently use mesenchymal stem cells (MSC). The aim of the...     

Stem Cells on the Brain: Modeling Neurodevelopmental and Neurodegenerative Diseases Using Human Induced Pluripotent Stem Cells

Seven years have passed since the initial report of the generation of induced pluripotent stem cells (iPSCs) from adult human somatic cells, and in the intervening time the field of neuroscience has developed numerous disease models using this technology. Here, we review progress in the field and describe both the advantages and potential pitfalls of modeling neurodegenerative and neurodevelopmental diseases using this technology. We include tables with information on neural differentiation protocols and studies that developed human iPSC lines to model neurological diseases. We also discuss how one can: investigate effects of genetic mutations with iPSCs, examine cell fate-specific phenotypes, best determine the specificity of a phenotype, and bring in vivo relevance to this in vitro technique.     

Interferon-Gamma Modification of Mesenchymal Stem Cells: Implications of Autologous and Allogeneic Mesenchymal Stem Cell Therapy in Allotransplantation

Bone marrow-derived mesenchymal stem cells (MSC) have unique immunomodulatory and reparative properties beneficial for allotransplantation cellular therapy. The clinical administration of autologous or allogeneic MSC with immunosuppressive drugs is able to prevent and treat allograft rejection in kidney transplant recipients, thus supporting the immunomodulatory role of MSC. Interferon-gamma (IFN-γ) is known to enhance the immunosuppressive properties of MSC. IFN-γ preactivated MSC (MSC-γ) directly or indirectly modulates T cell responses by enhancing or inducing MSC inhibitory factors. These factors are known to downregulate T cell activation, enhance T cell negative signalling, alter T cells from a proinflammatory to an anti-inflammatory phenotype, interact with antigen-presenting cells and increase or induce regulatory cells. Highly immunosuppressive MSC-γ with increased migratory and reparative capacities may aid tissue repair, prolong allograft survival and induce allotransplant tolerance in experimental models. Nevertheless, there are contradictory in vivo observations related to allogeneic MSC-γ therapy. Many studies report that allogeneic MSC are immunogenic due to their inherent expression of major histocompatibility (MHC) molecules. Enhanced expression of MHC in allogeneic MSC-γ may increase their immunogenicity and this can negatively impact allograft survival. Therefore, strategies to reduce MSC-γ immunogenicity would facilitate “off-the-shelf” MSC therapy to efficiently inhibit alloimmune rejection and promote tissue repair in allotransplantation. In this review, we examine the potential benefits of MSC therapy in the context of allotransplantation. We also discuss the use of autologous and allogeneic MSC and the issues associated with their immunogenicity in vivo, with particular focus on the use of enhanced MSC-γ cellular therapy.     

Role of Tissue-Specific Stem and Progenitor Cells in the Regeneration of the Pancreas and Testicular Tissue in Diabetic Disorders

Bulletin of Experimental Biology and Medicine - Using the model of hypogonadism in C57Bl/6 male mice, we showed that injection of streptozotocin to newborn animals and high-fat diet induced serum...     

人脐带、胎盘间充质干细胞样细胞中“干”性蛋白表达的研究

检测原代分离培养的人脐带、胎盘间充质干细胞样细胞中CD29、CD34、CD44、CD133、HLA-DR、vWF、MRP1、ABCG2 、P75NTR及Nestin的表达.采用组织块贴壁培养法分离培养人脐带、胎盘间充质干细胞样细胞,通过培养扩增后用流式细胞仪检测CD29、CD34、CD44、CD133、HLA-DR及vWF的表达,应用免疫荧光技术检测人脐带、胎盘间充质干细胞样细胞中MRP1、ABCG2、P75 NTR、Nestin的表达.在培养的人脐带、胎盘间充质干细胞样细胞中,流式细胞仪检测示CD29、CD44表达阳性,CD34、CD133、HLA-DR及vWF表达阴性;免疫荧光示MRP1、ABCG2 、P75NTR及Nestin在人脐带、胎盘间充质干细胞样细胞中表达阳性且荧光定位在细胞的胞浆.人脐带、胎盘间充质干细胞样细胞表达间充质干细胞的免疫表型;MRP1、ABCG2、P75NTR、Nestin在人脐带、胎盘间充质干细胞样细胞中表达阳性,提示人脐带与胎盘来源的间充质干细胞样细胞“干”性蛋白的表达情况相似.