Skeletal myogenic differentiation of mesenchymal stem cells isolated from human umbilical cord blood

Contribution of human muscle-derived cells to skeletal muscle regeneration in dystrophic host mice

BACKGROUND

Stem cell transplantation is a promising potential therapy for muscular dystrophies, but for this purpose, the cells need to be systemically-deliverable, give rise to many muscle fibres and functionally reconstitute the satellite cell niche in the majority of the patient's skeletal muscles. Human skeletal muscle-derived pericytes have been shown to form muscle fibres after intra-arterial transplantation in dystrophin-deficient host mice. Our aim was to replicate and extend these promising findings.

METHODOLOGY/PRINCIPAL FINDINGS

Isolation and maintenance of human muscle derived cells (mdcs) was performed as published for human pericytes. Mdscs were characterized by immunostaining, flow cytometry and RT-PCR; also, their ability to differentiate into myotubes in vitro and into muscle fibres in vivo was assayed. Despite minor differences between human mdcs and pericytes, mdscs contributed to muscle regeneration after intra-muscular injection in mdx nu/nu mice, the CD56+ sub-population being especially myogenic. However, in contrast to human pericytes delivered intra-arterially in mdx SCID hosts, mdscs did not contribute to muscle regeneration after systemic delivery in mdx nu/nu hosts.

CONCLUSIONS/SIGNIFICANCE

Our data complement and extend previous findings on human skeletal muscle-derived stem cells, and clearly indicate that further work is necessary to prepare pure cell populations from skeletal muscle that maintain their phenotype in culture and make a robust contribution to skeletal muscle regeneration after systemic delivery in dystrophic mouse models. Small differences in protocols, animal models or outcome measurements may be the reason for differences between our findings and previous data, but nonetheless underline the need for more detailed studies on muscle-derived stem cells and independent replication of results before use of such cells in clinical trials.

Promotion of cutaneous wound healing by local application of mesenchymal stem cells derived from human umbilical cord blood

This study aimed to determine whether mesenchymal stem cells (MSCs) derived from umbilical cord blood (UCB) would promote cutaneous wound healing. MSCs from human UCB were isolated and identified. The characteristics of the isolated MSCs' growth and proliferation were assayed in vitro. The MSCs labeled with 5-bromodeoxyuridine (BrdU) were applied on fresh cutaneous mice wounds. The healing rates were surveyed. The distribution and the differentiation into keratinocytes of the labeled MSCs in the wound tissue were checked by immunohistochemistry staining. The isolated MSCs could grow and proliferate well in vitro. The isolated MSCs from UCB could be labeled by 5-bromodeoxyuridine successfully. The MSCs derived from UCB could enhance the healing of mice skin defect wounds, and it was found that the implanted MSCs could differentiate into keratinocyte in the wound tissue. It was demonstrated that MSCs from UCB can be isolated and proliferated successfully. The local administration of MSCs derived from UCB improves skin defect wound healing in mice.

Human multipotent mesenchymal stromal cells from distinct sources show different in vivo potential to differentiate into muscle cells when injected in dystrophic mice

Limb-girdle muscular dystrophies are a heterogeneous group of disorders characterized by progressive degeneration of skeletal muscle caused by the absence or deficiency of muscle proteins. The murine model of Limb-Girdle Muscular Dystrophy 2B, the SJL mice, carries a deletion in the dysferlin gene. Functionally, this mouse model shows discrete muscle weakness, starting at the age of 4-6 weeks. The possibility to restore the expression of the defective protein and improve muscular performance by cell therapy is a promising approach for the future treatment of progressive muscular dystrophies (PMD). We and others have recently shown that human adipose multipotent mesenchymal stromal cells (hASCs) can differentiate into skeletal muscle when in contact with dystrophic muscle cells in vitro and in vivo. Umbilical cord tissue and adipose tissue are known rich sources of multipotent mesenchymal stromal cells (MSCs), widely used for cell-based therapy studies. The main objective of the present study is to evaluate if MSCs from these two different sources have the same potential to reach and differentiate in muscle cells in vivo or if this capability is influenced by the niche from where they were obtained. In order to address this question we injected human derived umbilical cord tissue MSCs (hUCT MSCs) into the caudal vein of SJL mice with the same protocol previously used for hASCs; we evaluated the ability of these cells to engraft into recipient dystrophic muscle after systemic delivery, to express human muscle proteins in the dystrophic host and their effect in functional performance. These results are of great interest for future therapeutic application.

Stem cells to treat muscular dystrophies - where are we?

The muscular dystrophies are inherited disorders characterised by progressive muscle wasting and weakness. Stem cell therapy is considered to be one of the most promising strategies for treating muscular dystrophies. In this review, we first examine the evidence that a stem cell could be used to treat muscular dystrophies, and then discuss the criteria that an ideal stem cell should meet. We also highlight the importance of standard operation procedures to be followed for ensuring the consistent and reproducible efficacy of a particular stem cell. While at the moment the scientific community is looking for an ideal stem cell to treat muscular dystrophies, it is clear that in order for this field to benefit from therapeutic stem cell applications, additional careful investigations are required.

Dental follicle stem cells and tissue engineering

Adult stem cells are multipotent and can be induced experimentally to differentiate into various cell lineages. Such cells are therefore a key part of achieving the promise of tissue regeneration. The most studied stem cells are those of the hematopoietic and mesenchymal lineages. Recently, mesenchymal stem cells were demonstrated in dental tissues, including dental pulp, periodontal ligament, and dental follicle. The dental follicle is a loose connective tissue that surrounds the developing tooth. Dental follicle stem cells could therefore be a cell source for mesenchymal stem cells. Indeed, dental follicle is present in impacted teeth, which are commonly extracted and disposed of as medical waste in dental practice. Dental follicle stem cells can be isolated and grown under defined tissue culture conditions, and recent characterization of these stem cells has increased their potential for use in tissue engineering applications, including periodontal and bone regeneration. This review describes current knowledge and recent developments in dental follicle stem cells and their application.

Mesenchymal stem cells as therapeutics

Mesenchymal stem cells (MSCs) are multipotent cells that are being clinically explored as a new therapeutic for treating a variety of immune-mediated diseases. First heralded as a regenerative therapy for skeletal tissue repair, MSCs have recently been shown to modulate endogenous tissue and immune cells. Preclinical studies of the mechanism of action suggest that the therapeutic effects afforded by MSC transplantation are short-lived and related to dynamic, paracrine interactions between MSCs and host cells. Therefore, representations of MSCs as drug-loaded particles may allow for pharmacokinetic models to predict the therapeutic activity of MSC transplants as a function of drug delivery mode. By integrating principles of MSC biology, therapy, and engineering, the field is armed to usher in the next generation of stem cell therapeutics.

Human mesenchymal stem cells and their use in cell-based therapies

The human population is increasingly facing various diseases, including types of cancer, that cannot be cured with conventional drugs. Advanced drug targeting of tumor cells is also often impossible when treating highly invasive and infiltrative tumors such as glioblastoma or pulmonary cancer, because of tumor cells' high migration and invasiveness. Pluripotent human mesenchymal stem cells (hMSCs) have been extensively studied, and strategies are being proposed for treating "incurable" cancers and injury/disease-affected organs. Because of their own intrinsic properties, involving homing and immunomodulatory potency, hMSCs could be used as an excellent cell/drug delivery vehicle in those cell-based therapies. Their unprecedented use has been shadowed, however, by their spontaneous transformation, which links them to cancer-initiating cells during tumor development. How malignant initiation proceeds in vivo, and what are the exact characteristics of the cancer-initiating cells, still remain to be investigated. In the present review, the authors summed up the most recent knowledge about hMSC characteristics, their malignant transformation, and outlined the possibilities of their safe use in novel cell-based therapies.

Encapsulation of mesenchymal stem cells from Wharton's jelly in alginate microbeads

The description of a microencapsulation procedure for Wharton's jelly mesenchymal stem cells (WJMSCs) is reported. The applied method is based on the generation of monodisperse droplets by a vibrational nozzle. An ionic alginate encapsulation procedure was utilized for the microbeads hardening. Different experimental parameters were analyzed, including frequency and amplitude of vibration, polymer pumping rate, and distance between the nozzle and the gelling bath. The produced barium-alginate microbeads were characterized by excellent morphological characteristics as well as a very narrow size distribution. The microencapsulation procedure did not alter the morphology and viability of the encapsulated WJMSCs. In addition, the current paper reports the functional properties in terms of secretive profiles of both free and encapsulated WJMSCs. The analyzed factors were members of the family of interleukins, chemokines, growth factors, and soluble forms of adhesion molecules. These experiments showed that despite encapsulation, most of the proteins analyzed were secreted both by the free and encapsulated cells, even if in a different extent. In conclusion, the described encapsulation procedure represents a promising strategy to utilize WJMSCs for possible in vivo applications in tissue engineering and biomedicine.

Application of human umbilical cord blood-derived mesenchymal stem cells in disease models

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) are regarded as an alternative source of bone marrow-derived mesenchymal stem cells because collection of cord blood is less invasive than that of bone marrow. hUCB-MSCs have recently been studied for evaluation of their potential as a source of cell therapy. In this review, the general characteristics of hUCB-MSCs and their therapeutic effects on various diseases in vitro and in vivo will be discussed.

Cells of extraembryonic mesodermal origin confer human dystrophin in the mdx model of Duchenne muscular dystrophy

Duchenne muscular dystrophy is an X-linked recessive genetic disease characterized by severe skeletal muscular degeneration. The placenta is considered to be a promising candidate cell source for cellular therapeutics because it contains a large number of cells and heterogenous cell populations with myogenic potentials. We analyzed the myogenic potential of cells obtained from six parts of the placenta, that is, umbilical cord, amniotic epithelium, amniotic mesoderm, chorionic plate, villous chorion, and decidua basalis. In vitro cells derived from amniotic mesoderm, chorionic plate, and villous chorion efficiently transdifferentiate into myotubes. In addition, in vivo implantation of placenta-derived cells into dystrophic muscles of immunodeficient mdx mice restored sarcolemmal expression of human dystrophin. Differential contribution to myogenesis in this study may be attributed to placental portion-dependent default cell state. Molecular taxonomic characterization of placenta-derived maternal and fetal cells in vitro will help determine the feasibility of cell-based therapy.

The contribution of human synovial stem cells to skeletal muscle regeneration

Stem cell therapy holds promise for treating muscle diseases. Although satellite cells regenerate skeletal muscle, they only have a local effect after intra-muscular transplantation. Alternative cell types, more easily obtainable and systemically-deliverable, were therefore sought. Human synovial stem cells (hSSCs) have been reported to regenerate muscle fibres and reconstitute the satellite cell pool. We therefore determined if these cells are able to regenerate skeletal muscle after intra-muscular injection into cryodamaged muscles of Rag2-/gamma chain-/C5-mice. We found that hSSCs possess only limited capacity to undergo myogenic differentiation in vitro or to contribute to muscle regeneration in vivo. However, this is enhanced by over-expression of human MyoD1. Interestingly, hSSCs express extracellular matrix components laminin alpha2 and collagen VI within grafted muscles. Therefore, despite their limited capacity to regenerate skeletal muscle, hSSCs could play a role in treating muscular dystrophies secondary to defects in extracellular matrix proteins.

Bone Fracture Healing with Umbilico-Placental Mononuclear Cells: A Controlled Animal Study

BACKGROUND

Fracture healing is a significant process in orthopedics. In this controlled animal study, our aimis to expose the healing effects of cord blood umbilico-placental mononuclear cells (UPMNCs) on bone fractures.

MATERIALS AND METHODS

Caesarean sections were performed on five pregnant New Zealand rabbits at term. Placentas and cords were collected. Standard closed transverse shaft fractures were created on both tibial bones of 15 baby rabbits. The right tibias were given UPMNCs; the left tibias were the control group. Histological examinations, osteoblast and osteoclast cell counts, and mechanical stabilities were compared. Anchorage of the donor cells was shown by the fluorescence in situ hybridization (FISH) technique.

RESULTS

In the group injected with UPMNCs, histopathological fracture healing was faster, osteoblast and osteoclast counts were significantly increased, and the maximum load capacity was higher. The presence of XX and XY chromatins on the same slide revealed the anchorage of female donor cells on male tissues.

CONCLUSION

The effects of umbilico-placental mononuclear cells on bone healing are histopathological healing priority, increased osteoblastic and osteoclastic activities (bone turnover), and better mechanical stability.

Mesenchymal stromal cells derived from human umbilical cord tissues: primitive cells with potential for clinical and tissue engineering applications

Mesenchymal stem or stromal cells (MSCs) have a high potential for cell-based therapies as well as for tissue engineering applications. Since Friedenstein first isolated stem or precursor cells from the human bone marrow (BM) stroma that were capable of osteogenesis, BM is currently the most common source for MSCs. However, BM presents several disadvantages, namely low frequency of MSCs, high donor-dependent variations in quality, and painful invasive intervention. Thus, tremendous research efforts have been observed during recent years to find alternative sources for MSCs.In this context, the human umbilical cord (UC) has gained more and more attention. Since the UC is discarded after birth, the cells are easily accessible without ethical concerns. This postnatal organ was found to be rich in primitive stromal cells showing typical characteristics of bone-marrow MSCs (BMSCs), e.g., they grow as plastic-adherent cells with a fibroblastic morphology, express a set of typical surface markers, and can be directly differentiated at least along mesodermal lineages. Compared to BM, the UC tissue bears a higher frequency of stromal cells with a higher in vitro expansion potential. Furthermore, immune-privileged and immune-modulatory properties are reported for UC-derived cells, which open highly interesting perspectives for clinical applications.

Gene expression profile of mesenchymal stem cells from paired umbilical cord units: cord is different from blood

Mesenchymal stem cells (MSC) are multipotent cells which can be obtained from several adult and fetal tissues including human umbilical cord units. We have recently shown that umbilical cord tissue (UC) is richer in MSC than umbilical cord blood (UCB) but their origin and characteristics in blood as compared to the cord remains unknown. Here we compared, for the first time, the exonic protein-coding and intronic noncoding RNA (ncRNA) expression profiles of MSC from match-paired UC and UCB samples, harvested from the same donors, processed simultaneously and under the same culture conditions. The patterns of intronic ncRNA expression in MSC from UC and UCB paired units were highly similar, indicative of their common donor origin. The respective exonic protein-coding transcript expression profiles, however, were significantly different. Hierarchical clustering based on protein-coding expression similarities grouped MSC according to their tissue location rather than original donor. Genes related to systems development, osteogenesis and immune system were expressed at higher levels in UCB, whereas genes related to cell adhesion, morphogenesis, secretion, angiogenesis and neurogenesis were more expressed in UC cells. These molecular differences verified in tissue-specific MSC gene expression may reflect functional activities influenced by distinct niches and should be considered when developing clinical protocols involving MSC from different sources. In addition, these findings reinforce our previous suggestion on the importance of banking the whole umbilical cord unit for research or future therapeutic use.

Comparison of mesenchymal stem cells derived from arterial, venous, and Wharton's jelly explants of human umbilical cord

We isolated mesenchymal stem cells (MSC) from arteries (UCA), veins (UCV), and Wharton's jelly (UCWJ) of human umbilical cords (UC) and determined their relative capacities for sustained proliferation and multilineage differentiation. Individual UC components were dissected, diced into 1-2 mm(3) fragments, and aligned in explant cultures from which migrating cells were isolated using trypsinization. Preparations from 13 UCs produced 13 UCWJ, 11 UCV, and 10 UCA cultures of fibroblast-like, spindle-shaped cells negative for CD31, CD34, CD45, CD271, and HLA-class II, but positive for CD13, CD29, CD44, CD73, CD90, CD105, and HLA-class I. UCV cells exhibited a significantly higher frequency of colony-forming units fibroblasts than did UCWJ and UCA cells. Individual MSCs could be selectively differentiated into osteoblasts, chondrocytes, and adipocytes. When compared for osteogenic potential, UCWJ cells were the least effective precursors, whereas UCA-derived cells developed alkaline phosphatase activity with or without an osteogenic stimulus. UC components, especially blood vessels, could provide a promising source of MSCs with important clinical applications.

Effect of human umbilical cord blood-derived mesenchymal stem cells in a cirrhotic rat model

BACKGROUND/AIM

Cirrhosis is a long-term consequence of chronic hepatic injury and no effective therapy is currently available for this disease. Recent reports have shown that the mesenchymal stem cells (MSCs) have the capacity to differentiate into hepatocytes, and umbilical cord blood is a rich source of MSCs. Hence, we investigated the effect of infusing of human umbilical cord blood-derived MSCs (HMSCs) in carbon tetrachloride (CCl4)-induced cirrhosis in a rat model.

METHODS

The effect of HMSCs on cirrhosis was evaluated using haematoxylin and eosin and Masson's trichrome staining. To evaluate cirrhosis-related factors, we measured protein and mRNA expression of transforming growth factor beta1 (TGF-beta1), collagen type I and alpha-smooth muscle actin (alpha-SMA).

RESULTS

Histological findings showed that liver fibrosis in rats was alleviated by HMSCs infusion. Interestingly, CM-DiI-labelled HMSCs expressed the hepatocyte-specific markers, human albumin and alpha-fetoprotein. Infusion of HMSCs significantly inhibited TGF-beta1, collagen type I and alpha-SMA expressions in CCl4-induced cirrhotic rats.

CONCLUSION

Our results showed that HMSCs infusion could improve liver fibrosis in rats with CCl4-induced cirrhosis, raising the possibility for clinical use of HMSCs in the treatment of cirrhosis.

Mesenchymal stem cells: emerging therapy for Duchenne muscular dystrophy

Multipotent cells that can give rise to bone, cartilage, fat, connective tissue, and skeletal and cardiac muscle are termed mesenchymal stem cells. These cells were first identified in the bone marrow, distinct from blood-forming stem cells. Based on the embryologic derivation, availability, and various pro-regenerative characteristics, research exploring their use in cell therapy shows great promise for patients with degenerative muscle diseases and a number of other conditions. In this review, the authors explore the potential for mesenchymal stem cell therapy in the emerging field of regenerative medicine with a focus on treatment for Duchenne muscular dystrophy.

Robust functional vascular network formation in vivo by cooperation of adipose progenitor and endothelial cells

Rapid induction and maintenance of blood flow through new vascular networks is essential for successfully treating ischemic tissues and maintaining function of engineered neo-organs. We have previously shown that human endothelial progenitor cells (EPCs) form functioning vessels in mice, but these are limited in number and persistence; and also that human adipose stromal cells (ASCs) are multipotent cells with pericytic properties which can stabilize vascular assembly in vitro. In this study, we tested whether ASCs would cooperate with EPCs to coassemble vessels in in vivo implants. Collagen implants containing EPCs, ASCs, or a 4:1 mixture of both were placed subcutaneously into NOD/SCID mice. After a range of time periods, constructs were explanted and evaluated with regard to vascular network assembly and cell fate; and heterotypic cell interactions were explored by targeted molecular perturbations. The density and complexity of vascular networks formed by the synergistic dual-cell system was many-fold higher than found in implants containing either ASCs or EPCs alone. Coimplantation of ASCs and EPCs with either pancreatic islets or adipocytes produced neoorgans populated by these parenchymal cells, as well as by chimeric human vessels conducting flow. This study is the first to demonstrate prompt and consistent assembly of a vascular network by human ASCs and endothelial cells and vascularization by these cells of parenchymal cells in implants. Mixture of these 2 readily available, nontransformed human cell types provides a practical approach to tissue engineering, therapeutic revascularization, and in vivo studies of human vasculogenesis.

Fetal mesenchymal stem cells: isolation, properties and potential use in perinatology and regenerative medicine

The fetus is a source of nonembryonic stem cells (SC), with potential applications in perinatal medicine. Cells derived from the placenta, membranes, amniotic fluid or fetal tissues are higher in number, expansion potential and differentiation abilities compared with SC from adult tissues. Although some obstacles keep SC biology at distance from clinical application, the feasibility of using (homologous) SC for tissue engineering for the fetus with a congenital birth defect has been demonstrated. Also, other pathologies may benefit from SC technology.

Stem cells from umbilical cord blood do have myogenic potential, with and without differentiation induction in vitro

The dystrophin gene, located at Xp21, codifies dystrophin, which is part of a protein complex responsible for the membrane stability of muscle cells. Its absence on muscle causes Duchenne Muscular Dystrophy (DMD), a severe disorder, while a defect of muscle dystrophin causes Becker Muscular Dystrophy (DMB), a milder disease. The replacement of the defective muscle through stem cells transplantation is a possible future treatment for these patients. Our objective was to analyze the potential of CD34+ stem cells from umbilical cord blood to differentiate in muscle cells and express dystrophin, in vitro. Protein expression was analyzed by Immunofluorescence, Western Blotting (WB) and Reverse Transcriptase – Polymerase Chain Reaction (RT-PCR). CD34+ stem cells and myoblasts from a DMD affected patient started to fuse with muscle cells immediately after co-cultures establishment. Differentiation in mature myotubes was observed after 15 days and dystrophin-positive regions were detected through Immunofluorescence analysis. However, WB or RT-PCR analysis did not detect the presence of normal dystrophin in co-cultures of CD34+ and DMD or DMB affected patients' muscle cells. In contrast, some CD34+ stem cells differentiated in dystrophin producers' muscle cells, what was observed by WB, reinforcing that this progenitor cell has the potential to originate muscle dystrophin in vitro, and not just in vivo like reported before.

Skeletal myogenesis by human primordial germ cell-derived progenitors

We have isolated and cultured human primordial germ cells (PGCs) from early embryos. The PGCs expressed embryonic germ (EG) cell-specific surface markers, including Oct4 and Nanos. We derived a cell population from these PGCs that we termed embryoid body-derived (EBD) cells. EBD cells can be extensively expanded in vitro for more than 50 passages and express lineage markers from all three primary germ layers. The myogenic potential of the EBD cells was examined both in vitro and in vivo.In vitro, the EBD cells can be induced to form multinucleated myotubes, which express late skeletal muscle-specific markers, including MHC and dystrophin, when exposed to human galectin-1. In vivo, the EBD cells gave rise to all the myogenic lineages, including the skeletal muscle stem cells known as satellite cells. Strikingly, these cells were able to partially restore degenerated muscles in the SCID/mdx mouse, an animal model of the Duchenne's muscular dystrophy. These results indicate the EBD cells may be a promising source of myogenic stem cells for cell-based therapies for muscle degenerative disorders.

Simultaneous isolation of vascular endothelial cells and mesenchymal stem cells from the human umbilical cord

The umbilical cord represents the link between mother and fetus during pregnancy. This cord is usually discarded as a biological waste after the child's birth; however, its importance as a "store house" of stem cells has been explored recently. We developed a method of simultaneous isolation of endothelial cells (ECs) from the vein and mesenchymal stem cells from umbilical cord Wharton's jelly of the same cord. The isolation protocol has been simplified, modified, and improvised with respect to choice of enzyme and enzyme mixture, digestion time, cell yield, cell growth, and culture medium. Isolated human umbilical vascular ECs (hUVECs) were positive for von-Willibrand factor, a classical endothelial marker, and could form capillary-like structures when seeded on Matrigel, thus proving their functionality. The isolated human umbilical cord mesenchymal stem cells (hUCMSCs) were found positive for CD44, CD90, CD 73, and CD117 and were found negative for CD33, CD34, CD45, and CD105 surface markers; they were also positive for cytoskeleton markers of smooth muscle actin and vimentin. The hUCMSCs showed multilineage differentiation potential and differentiated into adipogenic, chondrogenic, osteogenic, and neuronal lineages under influence of lineage specific differentiation medium. Thus, isolating endothelial cells as well as mesenchymal cells from the same umbilical cord could lead to complete utilization of the available tissue for the tissue engineering and cell therapy.

Regeneration and adult stem cells in the human female reproductive tract

The human uterus is unique in that it exhibits a tremendous regenerative capacity that enables cyclical regeneration and remodeling throughout a woman’s reproductive life. This plasticity of the reproductive system has recently been highlighted. Regeneration and remodeling in the female reproductive tract alludes to the existence of endometrial and myometrial stem cell systems, which has been supported by increasing experimental evidence. Characterization of these stem cells, along with the study of the mechanisms controlling their regeneration, will improve the understanding of the physiology and pathophysiology of the female reproductive tract.

Suppression of cellular immunity by cord blood-derived unrestricted somatic stem cells is cytokine-dependent

Unrestricted somatic stem cells (USSC) have the potential to differentiate into tissues derived from all three germinal layers and therefore hold promise for use in regenerative therapies. Furthermore, they have haematopoietic stromal activity, a characteristic that may be exploited to enhance haematopoietic engraftment. Both applications may require USSC to be used in an allogeneic, HLA-mismatched setting. We have therefore studied their in vitro interaction with cellular immunity. USSC showed no allostimulatory activity and caused only minimal inhibition of allogeneic T-cell responses. However, following pre-stimulation with IFNgamma and TNFalpha, they inhibited T-cell proliferation in an indoleamine 2, 3-dioxygenase-dependent manner and suppressed graft-versus-host type reactions. In addition, USSC inhibited DC maturation and function. This inhibition was overridden by stronger DC maturation signals provided by IL-1beta, IL-6, PGE(2) and TNFalpha compared to TNFalpha alone. Pre-stimulation of USSC with IFNgamma and TNFalpha had a similar effect: Inhibition of DC maturation was no longer observed. Thus, USSC are conditionally immunosuppressive, and IFNgamma and TNFalpha constitute a switch, which regulates their immunological properties. They either suppress T-cell responses in the presence of both cytokines or in their absence block DC differentiation and function. These activities may contribute to fine-tuning the immune system especially at sites of tissue damage in order to ensure appropriate differentiation of USSC and subsequent tissue repair. Therapeutically, they may help to protect USSC and possibly their progeny from immune rejection.

Brain-derived neurotrophic factor stimulates the neural differentiation of human umbilical cord blood-derived mesenchymal stem cells and survival of differentiated cells through MAPK/ERK and PI3K/Akt-dependent signaling pathways

Brain-derived neurotrophic factor (BDNF) plays an important role in the differentiation, development, and survival of neural stem cells. In this study, we analyzed its effects on the stimulation of human umbilical cord blood-derived mesenchymal stem cells in terms of their potential to differentiate into neuron-like cells, their survival characteristics, and the molecular mechanisms involved. The treatment of cells with neural induction medium (NIM) and BDNF generated more cells that were neuron-like and produced stronger expression of neural-lineage markers than cells treated with NIM and without BDNF. Raf-1 and ERK phosphorylation and p35 expression levels increased significantly in cells treated with both NIM and BDNF. This treatment also effectively blocked cell death following neural induction and increased Akt phosphorylation and Bcl2 expression compared with cells treated with NIM without BDNF. Inhibition of ERKs inhibited the BDNF-stimulated up-regulation of p35 and Bcl2. In addition, the inhibition of PI3K abrogated Akt phosphorylation and Bcl2 expression, but not p35 expression. Thus, MAPK/ERK-dependent p35 up-regulation and MAPK/ERK-dependent and PI3K/Akt-dependent Bcl2 up-regulation contribute to BDNF-stimulated neural differentiation and to the survival of differentiated cells.

Biologic characteristics of mesenchymal stromal cells and their clinical applications in pediatric patients

In the past few years, intensive research in the understanding of the biologic characteristics of the mesenchymal stromal cells has already led to some early clinical applications. The aim of this review is to summarize the latest information from basic science advances and the outcome of their use in clinical practice with a particular focus in pediatric patients. The minimum criteria required to identify mesenchymal stromal cells, their immunosuppressive-nonimmunogenic properties and their attribution in the treatment of graft-versus-host disease, in the acceleration of hematopoietic recovery, in tissue repair/tissue engineering and in the treatment of selected inherited disorders are discussed. Appropriate preclinical models, completion of ongoing and development of new clinical trials will establish the role of these cells in the treatment of both adult and pediatric patients.

A 37-year-old spinal cord-injured female patient, transplanted of multipotent stem cells from human UC blood, with improved sensory perception and mobility, both functionally and morphologically: a case study

HLA-matched UC blood-derived multipotent stem cells were directly transplanted into the injured spinal cord site of a 37-year-old female patient suffering from spinal cord injury (SPI). In this case, human cord blood (UCB)-derived multipotent stem cells improved sensory perception and movement in the SPI patient's hips and thighs within 41 days of cell transplantation. CT and MRI results also showed regeneration of the spinal cord at the injured site and some of the cauda equina below it. Therefore, it is suggested that UCB multipotent stem cell transplantation could be a good treatment method for SPI patients.

Human muscular fetal cells: a potential cell source for muscular therapies

Myoblast transfer therapy has been extensively studied for a wide range of clinical applications, such as tissue engineering for muscular loss, cardiac surgery or Duchenne Muscular Dystrophy treatment. However, this approach has been hindered by numerous limitations, including early myoblast death after injection and specific immune response after transplantation with allogenic cells. Different cell sources have been analyzed to overcome some of these limitations. The object of our study was to investigate the growth potential, characterization and integration in vivo of human primary fetal skeletal muscle cells. These data together show the potential for the creation of a cell bank to be used as a cell source for muscle cell therapy and tissue engineering. For this purpose, we developed primary muscular cell cultures from biopsies of human male thigh muscle from a 16-week-old fetus and from donors of 13 and 30 years old. We show that fetal myogenic cells can be successfully isolated and expanded in vitro from human fetal muscle biopsies, and that fetal cells have higher growth capacities when compared to young and adult cells. We confirm lineage specificity by comparing fetal muscle cells to fetal skin and bone cells in vitro by immunohistochemistry with desmin and 5.1 H11 antibodies. For the feasibility of the cell bank, we ensured that fetal muscle cells retained intrinsic characteristics after 5 years cryopreservation. Finally, human fetal muscle cells marked with PKH26 were injected in normal C57BL/6 mice and were found to be present up to 4 days. In conclusion we estimate that a human fetal skeletal muscle cell bank can be created for potential muscle cell therapy and tissue engineering.

Probing cellular microenvironments and tissue remodeling by atomic force microscopy

The function of cells is strongly determined by the properties of their extracellular microenvironment. Biophysical parameters like environmental stiffness and fiber orientation in the surrounding matrix are important determinants of cell adhesion and migration. Processes like tissue maintenance, wound repair, cancer cell invasion, and morphogenesis depend critically on the ability of cells to actively sense and remodel their surroundings. Pericellular proteolytic activity and adaptation of migration tactics to the environment are strategies to achieve this aim. Little is known about the distinct regulatory mechanisms that are involved in these processes. The system's critical biophysical and biochemical determinants are well accessible by atomic force microscopy (AFM), a unique tool for functional, nanoscale probing and morphometric, high-resolution imaging of processes in live cells. This review highlights common principles of tissue remodeling and focuses on application examples of different AFM techniques, for example elasticity mapping, the combination of AFM and fluorescence microscopy, the morphometric imaging of proteolytic activity, and force spectroscopy applications of single molecules or individual cells. To achieve a more complete understanding of the processes underlying the interaction of cells with their environments, the combination of AFM force spectroscopy experiments will be essential.

Umbilical cord blood mesenchymal stem cells

We studied umbilical cord blood mesenchymal stem cells and compared mesenchymal stem cells derived from umbilical cord blood, adipose tissue, and skin. Umbilical cord blood mesenchymal stem cells were characterized morphologically, cytofluorometrically, and by their differentiation potential. Umbilical cord blood mesenchymal stem cells did not differ from cells isolated from adipose tissue and skin by the main parameters (by morphology, expression of surface markers, and differentiation potential). A specific feature of umbilical cord blood mesenchymal stem cells is their low count per volume of the initial material and very low proliferative activity.

The potential of umbilical cord blood multipotent stem cells for nonhematopoietic tissue and cell regeneration

Stem cells have been isolated from human embryos, fetal tissue, umbilical cord blood (UCB), and also from "adult" sources. Adult stem cells are found in many tissues of the body and are capable of maintaining, generating, and replacing terminally differentiated cells. A source of pluripotent stem cells has been recently identified in UCB that can also differentiate across tissue lineage boundaries into neural, cardiac, epithelial, hepatocytic, and dermal tissue. Thus, UCB may provide a future source of stem cells for tissue repair and regeneration. Its widespread availability makes UCB an attractive source for tissue regeneration. UCB-derived stem cells offer multiple advantages over adult stem cells, including their immaturity, which may play a significant role in reduced rejection after transplantation into a mismatched host and their ability to produce larger quantities of homogenous tissue or cells. While research with embryonic stem cells continues to generate considerable controversy, human umbilical stem cells provide an alternative cell source that has been more ethically acceptable and appears to have widespread public support. This review will summarize the in vitro and in vivo studies examining UCB stem cells and their potential use for therapeutic application for nonhematopoietic tissue and cell regeneration.

Multipotent stem cells from umbilical cord: cord is richer than blood!

The identification of mesenchymal stem cell (MSC) sources that are easily obtainable is of utmost importance. Several studies have shown that MSCs could be isolated from umbilical cord (UC) units. However, the presence of MSCs in umbilical cord blood (UCB) is controversial. A possible explanation for the low efficiency of MSCs from UCB is the use of different culture conditions by independent studies. Here, we compared the efficiency in obtaining MSCs from unrelated paired UCB and UC samples harvested from the same donors. Samples were processed simultaneously, under the same culture conditions. Although MSCs from blood were obtained from only 1 of the 10 samples, we were able to isolate large amounts of multipotent MSCs from all UC samples, which were able to originate different cell lineages. Since the routine procedure in UC banks has been to store the blood and discard other tissues, such as the cord and/or placenta, we believe our results are of immediate clinical value. Furthermore, the possibility of originating different cell lines from the UC of neonates born with genetic defects may provide new cellular research models for understanding human malformations and genetic disorders, as well as the possibility of testing the effects of different therapeutic drugs.

A comparison of human umbilical cord matrix stem cells and temporomandibular joint condylar chondrocytes for tissue engineering temporomandibular joint condylar cartilage

The temporomandibular joint (TMJ) presents many problems in modern musculoskeletal medicine. Patients who suffer from TMJ disorders often experience a major loss in quality of life due to the debilitating effects that TMJ disorders can have on everyday activities. Cartilage tissue engineering can lead to replacement tissues that could be used to treat TMJ disorders. In this study, a spinner flask was used for a period of 6 days to seed polyglycolic acid (PGA) scaffolds with either TMJ condylar chondrocytes or mesenchymal-like stem cells derived from human umbilical cord matrix (HUCM). Samples were then statically cultured for 4 weeks either in growth medium containing chondrogenic factors or in control medium. Immunohistochemical staining of HUCM constructs after 4 weeks revealed a strong presence of collagen I and minute amounts of collagen II, whereas TMJ constructs revealed little collagen I and no collagen II. The HUCM constructs were shown to contain more GAGs than the TMJ constructs quantitatively at week 0 and histologically at week 4. Moreover, the cellularity of HUCM constructs was 55% higher at week 0 and nearly twice as high after 4 weeks, despite being seeded at the same density. The increased level of biosynthesis and higher cellularity of HUCM constructs clearly demonstrates that the HUCM stem cells outperformed the TMJ condylar cartilage cells under the prescribed conditions. HUCM stem cells may therefore be an attractive alternative to condylar cartilage cells for TMJ tissue engineering applications. Further, given the availability and ease of obtaining HUCM stem cells, these findings may have far-reaching implications, leading to novel developments in both craniofacial and orthopaedic tissue replacement therapies.

UC blood-derived mesenchymal stromal cells: an overview

The UC is a readily available source of blood that may be used for analysis and treatment. Some authors suggest that within the UC blood (UCB) are cells with potential for differentiation down mesenchymal lineages. Isolation and characterization of these cells has been accomplished in some centers. Differentiation of these cells down multiple lineages has been documented. Surface marker expression and gene expression profiling has been performed, and mesenchymal stromal cells (MSC) from BM and adipose tissue have been compared with those derived from UCB. The use of UCB-derived stem cells has been investigated in pre-clinical studies. As this field is rapidly advancing, this review summarizes the current state of our knowledge of MSC derived from UCB.

Osmotic Selection of Human Mesenchymal Stem/Progenitor Cells from Umbilical Cord Blood

The isolation of undifferentiated adult stem/progenitor cells remains a challenging task primarily due to the rare quantity of these cells in biological samples and the lack of unique markers. Herein, we report a relatively straightforward method for isolation of human mesenchymal stem cells (MSCs) based on their unusual resistance to osmotic lysis, which we term "osmotic selection" (OS). MSCs can remarkably withstand significant exposure to hypotonic conditions (> 30 min) with only a reversible impairment in cell proliferation and with no loss of stem cell potential after exposure. Comparison of MSCs to other circulating nonhematopoietic cells revealed a time regime, by which purification of these cells would be attainable without considerable cell loss. OS showed a 50-fold enrichment of fibroblast colony-forming units from umbilical cord blood samples when compared to commonly employed techniques. After upstream processing, isolated cells using OS were immunophenotyped to be CD14-, CD34-, CD45-, CD44+, CD105+, and CD106+, and displayed multipotent differentiation. Preliminary investigations to determine mechanisms responsible for osmolytic resistance revealed MSCs to have an ineffective volume of 59%, with the ability to double cell volume at infinite dilution. Disruption of filamentous actin polymerization by cytochalasin D sensitized MSCs to osmotic lysis, which suggests a cytoskeletal element involved in osmolytic resistance.

Isolation of progenitor cells from cord blood using adhesion matrices

The aim of this study was to develop optimal conditions for selective adhesion and isolation of mesenchymal progenitor cells (MPCs) from cord blood and to determine their potential for osteogenic differentiation. Mononuclear cells (MNCs) were isolated by Ficoll-Paque gradient and plated onto 48-well culture plates precoated with: human or bovine collagen type I, human collagen type IV, fibronectin or matrigel. Cultures were incubated in alphaMEM containing fetal calf serum. Viability of the adherent cells was determined by alamarBlue(R) assay after 2, 3, and 4 weeks. After 4 weeks in culture, cells were typsinized and replated. Primary cultures were analyzed by histochemistry and third passage cells by FACS. Isolated fibroblast-like cells were cultured in the presence of osteogenic factors and differentiation determined by Alizarin Red S staining, RT-PCR and electron dispersive spectroscopy (EDS). MNCs adhered to all types of matrices with the greatest adhesion rates on fibronectin. These cells were CD45(+), CD105(+), CD14(+), CD49a(+), CD49f(+), CD44(+) and CD34(-). The highest incidence of progenitor cells (PC) was observed on fibronectin and polystyrene. Passages were CD45(-), CD14(-), CD34(-) and weakly CD105(+). Primary cultures expressed endothelial/macrophage RNA markers whether cultured on fibronectin or polystyrene and these markers decreased upon passage. The best osteogenic differentiation was observed in MPCs cultured in osteogenic medium containing vitamin D(3) and FGF9. These cells expressed the bone-related mRNA, collagen type I, core binding factor I (Cbfa I), osteocalcin and osteopontin. EDS of deposits produced by these cells demonstrated a calcium/phosphate ratio parallel to hydroxyapatite. It was concluded that fibronectin increased adhesion rates and isolation potential of cord blood mesenchymal progenitor cells.

A hypothesis for an embryonic origin of pluripotent Oct-4(+) stem cells in adult bone marrow and other tissues

Accumulating evidence demonstrates that adult tissues contain a population of stem cells that express early developmental markers such as stage-specific embryonic antigen and transcription factors Oct-4 and Nanog. These are the markers characteristic for embryonic stem cells, epiblast stem cells and primordial germ cells. The presence of these stem cells in adult tissues including bone marrow, epidermis, bronchial epithelium, myocardium, pancreas and testes supports the concept that adult tissues contain some population of pluripotent stem cells that is deposited in embryogenesis during early gastrulation. In this review we will discuss these data and present a hypothesis that these cells could be direct descendants of the germ lineage. The germ lineage in order to pass genes on to the next generations creates soma and thus becomes a 'mother lineage' for all somatic cell lineages present in the adult body.

Stem cell strategies in burns care

The prospect of being able to replace damaged tissue by the process of regeneration would dramatically and irrevocably change the impact, management and outcome of burns. The current understanding of stem cell-based modulation and therapy together with their potential developments do bring this prospect ever closer to a clinical reality. This paper gives a background to stem cell strategies in burns care and identifies actual or prospective applications which, collectively, will forever change burns care throughout the world.

The role of mesenchymal stem cells in maintenance and repair of bone

The maintenance of stable bone mass during adult life, following rapid skeletal growth during childhood, is the result of a carefully controlled balance between the activities of bone forming (osteoblast) and bone resorbing (osteoclast) cells. Although skeletal turnover continues throughout adult life, the net effect of formation and resorption on bone mass is zero in healthy individuals. Later in life, bone mass begins to fall as resorption outpaces formation, particularly in post-menopausal women, which leads to increased fracture risk. The opposing actions of these two cell types are coupled by molecular interactions between them that are thought to be influenced by the actions of the precursor cells of the osteoblast lineage, mesenchymal stem cells (MSCs). In addition to regulating normal skeletal homeostasis, MSCs also play an important role in fracture repair. Bone fracture or injury initiates a series of cellular and molecular pathways that commence with hematoma formation and an inflammatory cascade that regulates MSCs activity leading to fracture healing and the reestablishment of skeletal integrity. Although tremendous strides have been made in increasing our understanding of bone biology, there is surprisingly little data about the role of MSCs in vivo in the maintenance of skeletal integrity or fracture repair. In recent years, the pivotal importance of anabolic therapies in the setting of osteoporosis in which bone mass is substantially increased above and beyond what is attainable with the bisphosphonate class of drugs has put MSC biology firmly on the scientific agenda. Although the biology of cultured MSCs is reasonably well understood, the biology of MSCs in vivo in both bone turnover and fracture repair remains poorly understood. The recent phenotypic characterization of in vivo MSCs and the ability to prospectively purify such cells will open up new avenues of research into a better understanding of the role of MSCs in bone turnover. The purpose of this article is to review bone and fracture biology from the perspective of recent advances in our understanding of MSCs and to highlight the major deficiencies in our current knowledge.

Term Amniotic membrane is a high throughput source for multipotent Mesenchymal Stem Cells with the ability to differentiate into endothelial cells in vitro

BACKGROUND

Term Amniotic membrane (AM) is a very attractive source of Mesenchymal Stem Cells (MSCs) due to the fact that this fetal tissue is usually discarded without ethical conflicts, leading to high efficiency in MSC recovery with no intrusive procedures. Here we confirmed that term AM, as previously reported in the literature, is an abundant source of hMSCs; in particular we further investigated the AM differentiation potential by assessing whether these cells may also be committed to the angiogenic fate. In agreement with the recommendation of the International Society for Cellular Therapy, the mesenchymal cells herein investigated were named Amniotic Membrane-human Mesenchymal Stromal Cells (AM-hMSC).

RESULTS

The recovery of hMSCs and their in vitro expansion potential were greater in amniotic membrane than in bone marrow stroma. At flow cytometry analysis AM-hMSCs showed an immunophenotypical profile, i.e., positive for CD105, CD73, CD29, CD44, CD166 and negative for CD14, CD34, CD45, consistent with that reported for bone marrow-derived MSCs. In addition, amniotic membrane-isolated cells underwent in vitro osteogenic (von Kossa stain), adipogenic (Oil Red-O stain), chondrogenic (collagen type II immunohistochemichal detection) and myogenic (RT-PCR MyoD and Myogenin expression as well as desmin immunohistochemical detection) differentiation. In angiogenic experiments, a spontaneous differentiation into endothelial cells was detected by in vitro matrigel assay and this behaviour has been enhanced through Vascular Endothelial Growth Factor (VEGF) induction. According to these findings, VEGF receptor 1 and 2 (FLT-1 and KDR) were basally expressed in AM-hMSCs and the expression of endothelial-specific markers like FLT-1 KDR, ICAM-1 increased after exposure to VEGF together with the occurrence of CD34 and von Willebrand Factor positive cells.

CONCLUSION

The current study suggests that AM-hMSCs may emerge as a remarkable tool for the cell therapy of multiple diseased tissues. AM-hMSCs may potentially assist both bone and cartilage repair, nevertheless, due to their angiogenic potential, they may also pave the way for novel approaches in the development of tissue-engineered vascular grafts which are useful when vascularization of ischemic tissues is required.

Isolation of progenitor cells from cord blood using adhesion matrices

The aim of this study was to develop optimal conditions for selective adhesion and isolation of mesenchymal progenitor cells (PCs) from cord blood and to determine their potential for osteogenic differentiation. Mononuclear cells (MNCs) were isolated by Ficoll-Paque gradient and plated onto 48-well culture plates precoated with: human or bovine collagen type I, human collagen type IV, fibronectin or matrigel. Cultures were incubated in alphaMEM containing fetal calf serum. Viability of the adherent cells was determined by alamarBlue(R) assay after 2, 3, and 4 weeks. After 4 weeks in culture, cells were typsinized and replated. Primary cultures were analyzed by histochemistry and third passage cells by FACS. Isolated fibroblast-like cells were cultured in the presence of osteogenic factors and differentiation determined by Alizarin Red S staining, RT-PCR and electron dispersive spectroscopy (EDS). MNCs adhered to all types of matrices with the greatest adhesion rates on fibronectin. These cells were CD45(+), CD105(+), CD14(+), CD49a(+), CD49f(+), CD44(+) and CD34(-). The highest incidence of PCs was observed on fibronectin and polystyrene. Passages were CD45(-), CD14(-), CD34(-) and weakly CD105(+). Primary cultures expressed endothelial/macrophage RNA markers whether cultured on fibronectin or polystyrene and these markers decreased upon passage. The best osteogenic differentiation was observed in MPCs cultured in osteogenic medium containing Vit D(3) and FGF9. These cells expressed the bone-related mRNA, collagen type I, core binding factor I (Cbfa I), osteocalcin and osteopontin. EDS of deposits produced by these cells demonstrated a calcium/phosphate ratio parallel to hydroxyapatite. It was concluded that fibronectin increased adhesion rates and isolation potential of cord blood mesenchymal progenitor cells.

Bone marrow-derived mesenchymal stem cells for regenerative medicine in craniofacial region

The craniofacial region contains many specified tissues including bone, cartilage, muscle, blood vessels and neurons. Defect or dysfunction of the craniofacial tissue after post-cancer ablative surgery, trauma, congenital malformations and progressive deforming skeletal diseases has a huge influence on the patient's life. Therefore, functional reconstruction of damaged tissues is highly expected. Bone marrow-derived mesenchymal stem cells (BMMSCs) are one of the most well characterized postnatal stem cell populations, and considered to be utilized for cell-based clinical therapies. Here, the current understanding and the potential applications in craniofacial tissue regeneration of BMMSCs are reviewed, and the current limitations and drawbacks are also discussed.