Human umbilical cord blood-derived CD34+ cells reverse osteoporosis in NOD/SCID mice by altering osteoblastic and osteoclastic activities

Combined application of mesenchymal stem cells and different glucocorticoid dosing alleviates osteoporosis in SLE murine models

OBJECTIVE

Bone mesenchymal stem cells (BMSCs) have been tentatively applied in the treatment of glucocorticoid-induced osteoporosis (GIOP) and systemic lupus erythematosus (SLE). However, the effects of BMSCs on osteoporosis within the context of glucocorticoid (GC) application in SLE remain unclear. Our aim was to explore the roles of BMSCs and different doses of GC interventions on osteoporosis in SLE murine models.

METHODS

MRL/MpJ-Faslpr mice were divided into eight groups with BMSC treatment and different dose of GC intervention. Three-dimensional imaging analysis and hematoxylin and eosin (H&E) staining were performed to observe morphological changes. The concentrations of osteoprotegerin (OPG) and receptor activator of nuclear factor κB ligand (RANKL) in serum were measured by enzyme-linked immunosorbent assay (ELISA). The subpopulation of B cells and T cells in bone marrows and spleens were analyzed by flow cytometry. Serum cytokines and chemokines were assessed using Luminex magnetic bead technology.

RESULTS

BMSCs ameliorated osteoporosis in murine SLE models by enhancing bone mass, improving bone structure, and promoting bone formation through increased bone mineral content and optimization of trabecular morphology. BMSC and GC treatments reduced the number of B cells in bone marrows, but the effect was not significant in spleens. BMSCs significantly promoted the expression of IL-10 while reducing IL-18. Moreover, BMSCs exert immunomodulatory effects by reducing Th17 expression and rectifying the Th17/Treg imbalance.

CONCLUSION

BMSCs effectively alleviate osteoporosis induced by SLE itself, as well as osteoporosis resulting from SLE combined with various doses of GC therapy. The therapeutic effects of BMSCs appear to be mediated by their influence on bone marrow B cells, T cell subsets, and associated cytokines. High-dose GC treatment exerts a potent anti-inflammatory effect but may hinder the immunotherapeutic potential of BMSCs. Our research may offer valuable guidance to clinicians regarding the use of BMSC treatment in SLE and provide insights into the judicious use of GCs in clinical practice.

Dexamethasone-induced muscle atrophy and bone loss in six genetically diverse collaborative cross founder strains demonstrates phenotypic variability by Rg3 treatment

Background

Osteosarcopenia is a common condition characterized by the loss of both bone and muscle mass, which can lead to an increased risk of fractures and disability in older adults. The study aimed to elucidate the response of various mouse strains to treatment with Rg3, one of the leading ginsenosides, on musculoskeletal traits and immune function, and their correlation.

Methods

Six Collaborative Cross (CC) founder strains induced muscle atrophy and bone loss with dexamethasone (15 mg/kg) treatment for 1 month, and half of the mice for each strain were orally administered Rg3 (20 mg/kg). Different responses were observed depending on genetic background and Rg3 treatment.

Results

Rg3 significantly increased grip strength, running performance, and expression of muscle and bone health-related genes in a two-way analysis of variance considering the genetic backgrounds and Rg3 treatment. Significant improvements in grip strength, running performance, bone area, and muscle mass, and the increased gene expression were observed in specific strains of PWK/PhJ. For traits related to muscle, bone, and immune functions, significant correlations between traits were confirmed following Rg3 administration compared with control mice. The phenotyping analysis was compiled into a public web resource called Rg3-OsteoSarco.

Conclusion

This highlights the complex interplay between genetic determinants, pathogenesis of muscle atrophy and bone loss, and phytochemical bioactivity and the need to move away from single inbred mouse models to improve their translatability to genetically diverse humans. Rg3-OsteoSarco highlights the use of CC founder strains as a valuable tool in the field of personalized nutrition.

Osteoporosis pathogenesis and treatment: existing and emerging avenues

Osteoporotic fractures lead to increased disability and mortality in the elderly population. With the rapid increase in the aging population around the globe, more effective treatments for osteoporosis and osteoporotic fractures are urgently required. The underlying molecular mechanisms of osteoporosis are believed to be due to the increased activity of osteoclasts, decreased activity of osteoblasts, or both, which leads to an imbalance in the bone remodeling process with accelerated bone resorption and attenuated bone formation. Currently, the available clinical treatments for osteoporosis have mostly focused on factors influencing bone remodeling; however, they have their own limitations and side effects. Recently, cytokine immunotherapy, gene therapy, and stem cell therapy have become new approaches for the treatment of various diseases. This article reviews the latest research on bone remodeling mechanisms, as well as how this underpins current and potential novel treatments for osteoporosis.

LncRNA AWPPH is downregulated in osteoporosis and regulates type I collagen α1 and α2 ratio

Normal ratio of type I collagen α1 to α2 (2:1) maintains normal bone microarchitecture. Altered ratios lead to formation of collagen homotrimers and deteriorated bone microarchitecture. In this study, we aimed to investigate the role of lncRNA AWPPH in osteoporosis. We observed that the expression of lncRNA AWPPH was downregulated in osteoporosis patients than that in healthy controls. Downregulated expression of lncRNA AWPPH distinguished osteoporosis patients from healthy controls. In vitro cell experiments showed that knockdown of lncRNA AWPPH led to upregulated α1 but downregulated expression of α2 in osteoblasts, which made the α1 to α2 ratio higher than 2:1. In contrast, overexpression of lncRNA AWPPH led to downregulated α1 but upregulated α2 in osteoblasts, which made the α1 to α2 ratio lower than 2:1. Therefore, lncRNA AWPPH is downregulated in osteoporosis and altered the expression of lncRNA AWPPH regulates type I collagen α1 and α2 ratio in osteoblasts.

A Review Into the Insights of the Role of Endothelial Progenitor Cells on Bone Biology

In addition to its important transport functions, the skeletal system is involved in complex biological activities for the regulation of blood vessels. Endothelial progenitor cells (EPCs), as stem cells of endothelial cells (ECs), possess an effective proliferative capacity and a powerful angiogenic capacity prior to their differentiation. They demonstrate synergistic effects to promote bone regeneration and vascularization more effectively by co-culturing with multiple cells. EPCs demonstrate a significant therapeutic potential for the treatment of various bone diseases by secreting a combination of growth factors, regulating cellular functions, and promoting bone regeneration. In this review, we retrospect the definition and properties of EPCs, their interaction with mesenchymal stem cells, ECs, smooth muscle cells, and immune cells in bone regeneration, vascularization, and immunity, summarizing their mechanism of action and contribution to bone biology. Additionally, we generalized their role and potential mechanisms in the treatment of various bone diseases, possibly indicating their clinical application.

The Therapeutic Potential of Hematopoietic Stem Cells in Bone Regeneration

The repair process of bone fractures is a complex biological mechanism requiring the recruitment and in situ functionality of stem/stromal cells from the bone marrow (BM). BM mesenchymal stem/stromal cells have been widely explored in multiple bone tissue engineering applications, whereas the use of hematopoietic stem cells (HSCs) has been poorly investigated in this context. A reasonable explanation is the fact that the role of HSCs and their combined effect with other elements of the hematopoietic niches in the bone-healing process is still elusive. Therefore, in this review we intend to highlight the influence of HSCs in the bone repair process, mainly through the promotion of osteogenesis and angiogenesis at the bone injury site. For that, we briefly describe the main biological characteristics of HSCs, as well as their hematopoietic niches, while reviewing the biomimetic engineered BM niche models. Moreover, we also highlighted the role of HSCs in translational in vivo transplantation or implantation as promoters of bone tissue repair.

Palmul-Tang, a Korean Medicine, Promotes Bone Formation via BMP-2 Pathway in Osteoporosis

Osteoporosis is a common skeletal disease in post-menopausal women. Palmul-tang, an herbal medicine, has been treated for gynecological disease such as anemia, anorexia, anti-fatigue, unspecified menstruation and female infertility in East Asia. In this study, ameliorative effects of Palmul-tang soft extracts (PMT), a Korean Medicine, on osteoporosis were investigated. Ovariectomized (OVX) osteoporotic ICR mice were intragastrically administrated PMT for 4 weeks. The level of bone mineral density (BMD) was analyzed in bone tissues by dual X-ray absorptiometry. The bone medullary cavity and deposition of collagen were investigated by histological analysis. In addition, the BMP-2 signaling-related molecules, osteoblastic differentiation and formation markers, were determined in femoral tissues. The levels of BMD and bone mineral content were significantly increased in tibia, femurs and LV by treatment of PMT. PMT replenished bone marrow cavity and increased collagen deposition in bone marrow cells of femur. In addition, administration of PMT recovered serum ALP, bALP, osteocalcin and calcium levels in osteoporotic mice. Moreover, PMT treatment up-regulated the expressions of BMP-2, RUNX2 and OSX with its downstream factors, ALP, OPN and BSP-1, in the femoral tissues. Taken together, PMT restored the bone minerals and improvement of bone integrity by bone-forming BMP-2 signaling pathway. These results demonstrate that PMT could be an ameliorative agent for osteoporosis.

Advances in mesenchymal stem cell transplantation for the treatment of osteoporosis

Osteoporosis is a systemic metabolic bone disease with characteristics of bone loss and microstructural degeneration. The personal and societal costs of osteoporosis are increasing year by year as the ageing of population, posing challenges to public health care. Homing disorders, impaired capability of osteogenic differentiation, senescence of mesenchymal stem cells (MSCs), an imbalanced microenvironment, and disordered immunoregulation play important roles during the pathogenesis of osteoporosis. The MSC transplantation promises to increase osteoblast differentiation and block osteoclast activation, and to rebalance bone formation and resorption. Preclinical investigations on MSC transplantation in the osteoporosis treatment provide evidences of enhancing osteogenic differentiation, increasing bone mineral density, and halting the deterioration of osteoporosis. Meanwhile, the latest techniques, such as gene modification, targeted modification and co-transplantation, are promising approaches to enhance the therapeutic effect and efficacy of MSCs. In addition, clinical trials of MSC therapy to treat osteoporosis are underway, which will fill the gap of clinical data. Although MSCs tend to be effective to treat osteoporosis, the urgent issues of safety, transplant efficiency and standardization of the manufacturing process have to be settled. Moreover, a comprehensive evaluation of clinical trials, including safety and efficacy, is still needed as an important basis for clinical translation.

Dihydrotestosterone and 17-Estradiol Enhancement of in vitro Osteogenic Differentiation of Castrated Male Rat Bone Marrow Mesenchymal Stem Cells (rBMMSCs)

Background: In vitro impact of dihydrotestosterone (DHT) and 17-estradiol (E2) in osteogenic differentiation of castrated rat bone marrow mesenchymal stem cells (rBMMSC) still need to be clarified. Materials and Methods: The viability, proliferation and density of cultured rBMMSC isolated from sham operated (Sham) and castrated (Cast) male rats were evaluated. rBMMSC were cultured with osteogenic differentiating medium (ODM) in the presence of DHT (5,10 nM) and E2 (10,100 nM). Osteogenesis was evaluated by alizarin red staining and measurement of calcium deposition and bone alkaline phosphatase (B-ALP) activity. Results: Population doubling (PD) of rBMMSC isolated from Cast rats was significantly lower (P<0.05) compared to that isolated from Sham rats. rBMMSC from Cast rats showed low scattered calcified nodule after culturing in ODM and did not cause a significant increase in calcium deposition and B-ALP activity compared to rBMMSCs from Sham rats. Exposure of rBMMSC isolated from Cast rats to DHT (5 nM) or E2 (10 nM) in ODM showed medium scattered calcified nodules with significantly higher (P<0.05) calcium deposition and B-ALP activity. Moreover, exposure of rBMMSC to DHT (10 nM) or E2 (100 nM) showed high scattered calcified nodules with higher (P<0.01) calcium deposition and B-ALP activity Conclusion: These results indicated that the presence of testes might participate in controlling the in vitro proliferation and osteogenic differentiation capacity of rBMMSCs. DHT and E2 can enhance the osteogenic capacity of rBMMSCs in a dose-dependent manner. Based on these observations, optimum usage of DHT and E2 can overcome the limitations of MSCs and advance the therapeutic bone regeneration potential in the future.

Stem cells in Osteoporosis: From Biology to New Therapeutic Approaches

Osteoporosis is a systemic disease that affects the skeleton, causing reduction of bone density and mass, resulting in destruction of bone microstructure and increased risk of bone fractures. Since osteoporosis is a disease affecting the elderly and the aging of the world's population is constantly increasing, it is expected that the incidence of osteoporosis and its financial burden on the insurance systems will increase continuously and there is a need for more understanding this condition in order to prevent and/or treat it. At present, available drug therapy for osteoporosis primarily targets the inhibition of bone resorption and agents that promote bone mineralization, designed to slow disease progression. Safe and predictable pharmaceutical means to increase bone formation have been elusive. Stem cell therapy of osteoporosis, as a therapeutic strategy, offers the promise of an increase in osteoblast differentiation and thus reversing the shift towards bone resorption in osteoporosis. This review is focused on the current views regarding the implication of the stem cells in the cellular and physiologic mechanisms of osteoporosis and discusses data obtained from stem cell-based therapies of osteoporosis in experimental animal models and the possibility of their future application in clinical trials.

TNX deficiency results in bone loss due to an increase in multinucleated osteoclasts

Tenascin-X (TNX), a glycoprotein of the extracellular matrix (ECM), is expressed in various tissues and plays an important role in ECM architecture. The TNXB gene encoding TNX is known as the gene responsible for classic-like Ehlers-Danlos syndrome (clEDS). To date, the role of TNX in dermal, muscular and obstetric features has been reported, but its role in bone homeostasis remains to be clarified. In this study, we found significant bone loss and upregulation of osteoclast marker gene expression in TNX-deficient mice. Further, TNX deficiency in the bone marrow promoted multinucleation of osteoclasts and resulted in increased bone resorption activity. These results indicate that multinucleated osteoclasts are the cause of bone loss in a TNX-deficient environment. Our findings provide new insight into the mechanism of osteoclast differentiation mediated by TNX and the pathology of clEDS.

Xenograft of Human Umbilical Mesenchymal Stem Cells from Wharton's Jelly Differentiating into Osteocytes and Reducing Osteoclast Activity Reverses Osteoporosis in Ovariectomized Rats

We examined the effects of human umbilical cord-derived mesenchymal stem cells (HUMSCs) in Wharton's jelly on ovariectomy (OVX)-induced osteoporosis by using in vitro and in vivo experiments. Two months after OVX, the rats gained weight and had a decreased serum estradiol level . Both micro-computed tomography (micro-CT) and histochemical analyses revealed a marked decrease in the bone volume (BV) and collagen content within the head, neck, and distal condyle of the femur, indicating that the osteoporosis animal model was successfully established 2 mo after bilateral OVX. Subsequently, 2.5 × 10⁶ HUMSCs were injected into the bone marrow cavity of the left femurs 2 mo after OVX. The rats were divided into the following groups: normal + phosphate-buffered saline (PBS), normal + HUMSCs, OVX + PBS, and OVX + HUMSCs. Two months after transplantation, both micro-CT imaging and histochemical staining revealed that the normal + HUMSCs group had higher BV and collagen content in the epiphysis and metaphysis than did the normal + PBS group. In the OVX + HUMSCs group, a substantial increase in the rod-shaped trabecular bone and the abundant accumulation of collagen were observed around the site of HUMSC transplantation. Plenty of transplanted HUMSCs remained viable and differentiated into osteoblasts. In addition, HUMSC transplantation reduced the number of osteoclasts. Compared with HUMSCs cultured alone, HUMSCs cocultured with osteoblasts showed that the percentage of cells differentiating into osteoblasts significantly increased. Furthermore, osteoclasts cocultured with HUMSCs had significantly decreased cellular activity and differentiation capability. HUMSC transplantation into the distal femur of OVX rats could locally stimulate osteocalcin synthesis, increase the trabecular bone, and inhibit osteoclast activity.

Ferutinin directs dental pulp-derived stem cells towards the osteogenic lineage by epigenetically regulating canonical Wnt signaling

Osteoporosis is a silent systemic disease that causes bone deterioration, and affects over 10 million people in the US alone. This study was undertaken to develop a potential stem cell therapy for osteoporosis. We have isolated and expanded human dental pulp-derived stem cells (DPSCs), characterized them, and confirmed their multipotential differentiation abilities. Stem cells often remain quiescent and require activation to differentiate and function. Herein, we show that ferutinin activates DPSCs by modulating the Wnt/β-catenin signaling pathway and key osteoblast-secreted proteins osteocalcin and collagen 1A1 both mRNA and protein levels. To confirm that ferutinin modulates the Wnt pathway, we inhibited glycogen synthase kinase 3 (GSK3) and found that protein expression patterns were similar to those found in ferutinin-treated DPSCs. To evaluate the role of ferutinin in epigenetic regulation of canonical Wnt signaling, the pathway molecules Wnt3a and Dvl3 were analyzed using chromatin immunoprecipitation (ChIP)-quantitative PCR approaches. We confirmed that active marks of both H3K9 acetylation and H3K4 trimethylation were significantly enhanced in the promoter sites of the WNT3A and DVL3 genes in DPSCs after addition of ferutinin. These data provide evidence that ferutinin activates and promotes osteogenic differentiation of DPSCs, and could be used as an inducer as a potentially effective stem cell therapy for osteoporosis.

Bone marrow mesenchymal stem cells stimulated with low-intensity pulsed ultrasound: Better choice of transplantation treatment for spinal cord injury: Treatment for SCI by LIPUS-BMSCs transplantation

Stem cell transplantation, especially treatment with bone marrow mesenchymal stem cells (BMSCs), has been considered a promising therapy for the locomotor and neurological recovery of spinal cord injury (SCI) patients. However, the clinical benefits of BMSCs transplantation remain limited because of the considerably low viability and inhibitory microenvironment. In our research, low-intensity pulsed ultrasound (LIPUS), which has been widely applied to clinical applications and fundamental research, was employed to improve the properties of BMSCs. The most suitable intensity of LIPUS stimulation was determined. Furthermore, the optimized BMSCs were transplanted into the epicenter of injured spinal cord in rats, which were randomized into four groups: (a) Sham group (n = 10), rats received laminectomy only and the spinal cord remained intact. (b) Injury group (n = 10), rats with contused spinal cord subjected to the microinjection of PBS solution. (c) BMSCs transplantation group (n = 10), rats with contused spinal cord were injected with BMSCs without any priming. (d) LIPUS-BMSCs transplantation group (n = 10), BMSCs stimulated with LIPUS were injected at the injured epicenter after contusion. Rats were then subjected to behavioral tests, immunohistochemistry, and histological observation. It was found that BMSCs stimulated with LIPUS obtained higher cell viability, migration, and neurotrophic factors expression in vitro. The rate of apoptosis remained constant. After transplantation of BMSCs and LIPUS-BMSCs postinjury, locomotor function was significantly improved in LIPUS-BMSCs transplantation group with higher level of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the epicenter, and the expression of neurotrophic receptor was also enhanced. Histological observation demonstrated reduced cavity formation in LIPUS-BMSCs transplantation group when comparing with other groups. The results suggested LIPUS can improve BMSCs viability and neurotrophic factors expression in vitro, and transplantation of LIPUS-BMSCs could promote better functional recovery, indicating possible clinical application for the treatment of SCI.

Synthetic Nanofiber-Reinforced Amniotic Membrane via Interfacial Bonding

Severe damage to the ocular surface can result in limbal stem cell (LSC) deficiency, which contributes to loss of corneal clarity, potential vision loss, chronic pain, photophobia, and keratoplasty failure. Human amniotic membrane (AM) is the most effective substrate for LSC transplantation to treat patients with LSC deficiency. However, the widespread use of the AM in the clinic remains a challenge because of the high cost for preserving freshly prepared AM and the weak mechanical strength of lyophilized AM. Here, we developed a novel composite membrane consisting of an electrospun bioabsorbable polymer fiber mesh bonded to a decellularized AM (dAM) sheet through interfacial conjugation. This membrane engineering approach drastically improved the tensile property and toughness of dAM, preserved similar levels of bioactivities as the dAM itself in supporting LSC attachment, growth, and maintenance, and retained significant anti-inflammatory capacity. These results demonstrate that the lyophilized nanofiber-dAM composite membrane offers superior mechanical properties for easy handling and suturing to the dAM, while presenting biochemical cues and basement membrane structure to facilitate LSC transplantation. This composite membrane exhibits major advantages for clinical applications in treating soft tissue damage and LSC deficiency.

Transplantation of Hepatocyte Growth Factor-Modified Dental Pulp Stem Cells Prevents Bone Loss in the Early Phase of Ovariectomy-Induced Osteoporosis

Investigations based on mesenchymal stem cells (MSCs) for osteoporosis have attracted attention recently. MSCs can be derived from various tissues, such as bone marrow, adipose, umbilical cord, placenta, and dental pulp. Among these, dental pulp-derived MSCs (DPSCs) and hepatocyte growth factor (HGF)-modified DPSCs (DPSCs-HGF) highly express osteogenic-related genes and have stronger osteogenic differentiation capacities. DPSCs have more benefits in treating osteoporosis. The purpose of this study was to investigate the roles of HGF gene-modified DPSCs in bone regeneration using a mouse model of ovariectomy (OVX)-induced bone loss. The HGF and luciferase genes were transferred into human DPSCs using recombinant adenovirus. These transduced cells were assayed for distribution or bone regeneration assay by transplantation into an OVX-induced osteoporosis model. By using bioluminogenic imaging, it was determined that some DPSCs could survive for >1 month in vivo. The DPSCs were mainly distributed to the lung in the early stage and to the liver in the late stage of OVX osteoporosis after administration, but they were scarcely distributed to the bone. The homing efficiency of DPSCs is higher when administrated in the early stage of a mouse OVX model. Micro-computed tomography indicated that DPSCs-Null or DPSCs-HGF transplantation significantly reduces OVX-induced bone loss in the trabecular bone of the distal femur metaphysis, and DPSCs-HGF show a stronger capacity to reduce bone loss. The data suggest that systemic infusion of DPSCs-HGF is a potential therapeutic approach for OVX-induced bone loss, which might be mediated by paracrine mechanisms.

Effects of Osteogenic-Conditioned Medium from Human Periosteum-Derived Cells on Osteoclast Differentiation

Stem/progenitor cell-based regenerative medicine using the osteoblast differentiation of mesenchymal stem cells (MSCs) is regarded as a promising approach for the therapeutic treatment of various bone defects. The effects of the osteogenic differentiation of stem/progenitor cells on osteoclast differentiation may have important implications for use in therapy. However, there is little data regarding the expression of osteoclastogenic proteins during osteoblastic differentiation of human periosteum-derived cells (hPDCs) and whether factors expressed during this process can modulate osteoclastogenesis. In the present study, we measured expression of RANKL in hPDCs undergoing osteoblastic differentiation and found that expression of RANKL mRNA was markedly increased in these cells in a time-dependent manner. RANKL protein expression was also significantly enhanced in osteogenic-conditioned media from hPDCs undergoing osteoblastic differentiation. We then isolated and cultured CD34+ hematopoietic stem cells (HSCs) from umbilical cord blood (UCB) mononuclear cells (MNCs) and found that these cells were well differentiated into several hematopoietic lineages. Finally, we co-cultured human trabecular bone osteoblasts (hOBs) with CD34+ HSCs and used the conditioned medium, collected from hPDCs during osteoblastic differentiation, to investigate whether factors produced during osteoblast maturation can affect osteoclast differentiation. Specifically, we measured the effect of this osteogenic-conditioned media on expression of osteoclastogenic markers and osteoclast cell number. We found that osteoclastic marker gene expression was highest in co-cultures incubated with the conditioned medium collected from hPDCs with the greatest level of osteogenic maturation. Although further study will be needed to clarify the precise mechanisms that underlie osteogenic-conditioned medium-regulated osteoclastogenesis, our results suggest that the osteogenic maturation of hPDCs could promote osteoclastic potential.

Effect of Stem Cell Therapy on Bone Mineral Density: A Meta-Analysis of Preclinical Studies in Animal Models of Osteoporosis

Background

Preclinical studies of the therapeutic role of stem cell based therapy in animal models of osteoporosis have largely yielded inconsistent results. We performed a meta-analysis to provide an overview of the currently available evidence.

Methods

Pubmed, Embase and Cochrane Library databases were systematically searched for relevant controlled studies. A random-effect model was used for pooled analysis of the effect of stem cell based therapy on bone mineral density (BMD). Stratified analyses were performed to explore the effect of study characteristics on the outcomes.

Results

Pooled results from 12 preclinical studies (110 animals in stem cell treatment groups, and 106 animals in control groups) indicated that stem cell based treatment was associated with significantly improved BMD (standardized mean difference [SMD] = 1.29, 95% Confidence Interval [CI]: 0.84–1.74, P < 0.001) with moderate heterogeneity (Cochrane’s Q test: P = 0.02, I² = 45%) among the constituent studies. Implantation of bone marrow cells, bone marrow mesenchymal stem cells, adipose-derived stem cells, and human umbilical cord blood-derived CD34+ cells, were all associated with improved BMD as compared to that in the controls (P < 0.05 for all); the only exception being the use of embryonic stem cell transplantation (P > 0.05). Egger’s test detected potential publication bias (P = 0.055); however, ‘trim and fill’ analysis yielded similar results after statistically incorporating the hypothetical studies in the analysis (SMD = 1.24, 95% CI: 0.32–2.16, P < 0.001).

Conclusions

Stem cell transplantation may improve BMD in animal models of osteoporosis. Our meta-analysis indicates a potential therapeutic role of stem cell based therapy for osteoporosis, and serves to augment the rationale for clinical studies.

The hematopoietic system in the context of regenerative medicine

Hematopoietic stem cells (HSC) represent the prototype stem cell within the body. Since their discovery, HSC have been the focus of intensive research, and have proven invaluable clinically to restore hematopoiesis following inadvertent radiation exposure and following radio/chemotherapy to eliminate hematologic tumors. While they were originally discovered in the bone marrow, HSC can also be isolated from umbilical cord blood and can be "mobilized" peripheral blood, making them readily available in relatively large quantities. While their ability to repopulate the entire hematopoietic system would already guarantee HSC a valuable place in regenerative medicine, the finding that hematopoietic chimerism can induce immunological tolerance to solid organs and correct autoimmune diseases has dramatically broadened their clinical utility. The demonstration that these cells, through a variety of mechanisms, can also promote repair/regeneration of non-hematopoietic tissues as diverse as liver, heart, and brain has further increased their clinical value. The goal of this review is to provide the reader with a brief glimpse into the remarkable potential HSC possess, and to highlight their tremendous value as therapeutics in regenerative medicine.

Mechanism and Treatment Strategy of Osteoporosis after Transplantation

Osteoporosis (OP) has emerged as a frequent and devastating complication of organ solid transplantation process. Bone loss after organ transplant is related to adverse effects of immunosuppressants on bone remodeling and bone quality. Many factors contribute to the pathogenesis of OP in transplanted patients. Many mechanisms of OP have been deeply approached. Drugs for OP can be generally divided into "bone resorption inhibitors" and "bone formation accelerators," the former hindering bone resorption by osteoclasts and the latter increasing bone formation by osteoblasts. Currently, bisphosphonates, which are bone resorption inhibitors drugs, are more commonly used clinically than others. Using the signaling pathway or implantation bone marrow stem cell provides a novel direction for the treatment of OP, especially OP after transplantation. This review addresses the mechanism of OP and its correlation with organ transplantation, lists prevention and management of bone loss in the transplant recipient, and discusses the recipients of different age and gender.

Retention of stemness and vasculogenic potential of human umbilical cord blood stem cells after repeated expansions on PES-nanofiber matrices

Despite recent advances in cardiovascular medicine, ischemic diseases remain a major cause of morbidity and mortality. Although stem cell-based therapies for the treatment of ischemic diseases show great promise, limited availability of biologically functional stem cells mired the application of stem cell-based therapies. Previously, we reported a PES-nanofiber based ex vivo stem cell expansion technology, which supports expansion of human umbilical cord blood (UCB)-derived CD133(+)/CD34(+) progenitor cells ∼225 fold. Herein, we show that using similar technology and subsequent re-expansion methods, we can achieve ∼5 million-fold yields within 24 days of the initial seeding. Interestingly, stem cell phenotype was preserved during the course of the multiple expansions. The high level of the stem cell homing receptor, CXCR4 was expressed in the primary expansion cells, and was maintained throughout the course of re-expansions. In addition, re-expanded cells preserved their multi-potential differential capabilities in vitro, such as, endothelial and smooth muscle lineages. Moreover, biological functionality of the re-expanded cells was preserved and was confirmed by a murine hind limb ischemia model for revascularization. These cells could also be genetically modified for enhanced vasculogenesis. Immunohistochemical evidences support enhanced expression of angiogenic factors responsible for this enhanced neovascularization. These data further confirms that nanofiber-based ex-vivo expansion technology can generate sufficient numbers of biologically functional stem cells for potential clinical applications.

Stem cell therapy for osteoporosis

Osteoporosis is a debilitating disease that affects millions of people worldwide. Current osteoporosis treatments are predominantly bone-resorbing drugs that are associated with several side effects. The use of stem cells for tissue regeneration has raised great hope in various fields of medicine, including musculoskeletal disorders. Stem cell therapy for osteoporosis could potentially reduce the susceptibility of fractures and augment lost mineral density by either increasing the numbers or restoring the function of resident stem cells that can proliferate and differentiate into bone-forming cells. Such osteoporosis therapies can be carried out by exogenous introduction of mesenchymal stem cells (MSCs), typically procured from bone marrow, adipose, and umbilical cord blood tissues or through treatments with drugs or small molecules that recruit endogenous stem cells to osteoporotic sites. The main hurdle with cell-based osteoporosis therapy is the uncertainty of stem cell fate and biodistribution following cell transplantation. Therefore, future advancements will focus on long-term engraftment and differentiation of stem cells at desired bone sites for tangible clinical outcome.

Stem cells for osteodegenerative diseases: current studies and future outlook

As the worldwide population grows and life expectancies continue to increase, degenerative diseases of the bones, muscles, and connective tissue are a growing problem for society. Current therapies for osteodegenerative disorders such as hormone replacement therapies, calcium/vitamin D supplements and oral bisphosphonates are often inadequate to stop degeneration and/or have serious negative side effects. Thus, there is an urgent need in the medical community for more effective and safer treatments. Stem cell therapies for osteodegenerative disorders have been rigorously explored over the last decade and are yielding some promising results in animal models and clinical trials. Although much work still needs to be done to ensure the safety and efficacy of these therapies, stem cells represent a new frontier of exciting possibilities for bone and cartilage regeneration.

Nanofiber-expanded human umbilical cord blood-derived CD34(+) cell therapy accelerates cutaneous wound closure in NOD/SCID mice

Nanofiber-expanded human umbilical cord blood–derived CD34⁺ cell therapy has been shown to have potential applications for peripheral and myocardial ischaemic diseases. However, the efficacies of expanded CD34⁺ cell therapy for treating cutaneous wounds and its mechanisms of action have yet to be established. Using an excisional wound model in non-obese diabetic/severe combined immune deficient mice, we show herein that CD34⁺ cells accelerate the wound-healing process by enhancing collagen synthesis, and increasing fibroblast cell migration within the wound bed. Concomitantly, reduced levels of matrix metalloproteinase (MMPs) such as MMP1, MMP3, MMP9 and MMP13 were detected in the wound beds of animals treated with CD34⁺ cells compared with vehicle-treated controls. CD34⁺ cells were found to mediate enhanced migration and proliferation of dermal fibroblast cells in vitro. Moreover, CD34⁺ cells secrete collagen in a serum-deprived environment. In mechanistic studies, co-culture of CD34⁺ cells with primary skin fibroblasts increased the expression of collagen1A1, a component of type 1 collagen, and decreased the expression of MMP1 in fibroblast cells in the presence of a proteasome inhibitor. Finally, CD34⁺ cell–mediated functions were transcriptionally regulated by the c-Jun N-terminal kinases pathway. Collectively, these data provide evidence of therapeutic efficacy and a novel mechanism of nanofiber-expanded CD34⁺ cell–mediated accelerated wound healing.

Generation of osteoporosis in immune-compromised mice for stem cell therapy

To evaluate therapeutic efficacy and to investigate involved molecular mechanisms of cell-based therapy in osteoporosis, the generation of a clinically relevant model is critically important. Herein, we describe detailed methods in generation of an immune-deficient osteoporotic murine model, and application of human umbilical cord blood-derived stem cells to assess their therapeutic efficacy.

Nanofiber-expanded human umbilical cord blood-derived CD34+ cell therapy accelerates murine cutaneous wound closure by attenuating pro-inflammatory factors and secreting IL-10

Nanofiber-expanded human umbilical cord blood-derived CD34+ cell therapy is under consideration for treating peripheral and cardiac ischemia. However, the therapeutic efficacy of nanofiber-expanded human umbilical cord blood-derived (NEHUCB) CD34+ cell therapy for wound healing and its mechanisms are yet to be established. Using an excision wound model in NOD/SCID mice, we show herein that NEHUCB-CD34+ cells home to the wound site and significantly accelerate the wound-healing process compared to vehicle-treated control. Histological analysis reveals that accelerated wound closure is associated with the re-epithelialization and increased angiogenesis. Additionally, NEHUCB-CD34+ cell-therapy decreases expression of pro-inflammatory cytokines, such as TNF-α, IL-1β, IL-6 and NOS2A in the wound bed, and concomitantly increases expression of IL-10 compared to vehicle-treated control. These findings were recapitulated in vitro using primary dermal fibroblasts and NEHUCB-CD34+ cells. Moreover, NEHUCB-CD34+ cells attenuate NF-κB activation and nuclear translocation in dermal fibroblasts through enhanced secretion of IL-10, which is known to bind to NF-κB and suppress transcriptional activity. Collectively, these data provide novel mechanistic evidence of NEHUCB-CD34+ cell-mediated accelerated wound healing.

Hematopoietic stem cells improve dopaminergic neuron in the MPTP-mice

Because of their ability for self-renewal and neural differentiation, stem cells are believed to be ideal for cell replacement therapy in Parkinson's disease (PD). Nanofiber-expanded human umbilical cord hematopoietic stem cells (HUHSCs) are advantageous to other stem cells as they provide a source of unlimited stem cell production for clinical application. In this study, we investigated whether 1. nanofiber-expanded HUHSCs are capable of neural differentiation in vitro, and 2. they could improve dopaminergic neuron morphology in the caudate/putamen (CPu) and substantia nigra pars compacta (SNc) of the MPTP-mouse model of PD. When cultured under neural differentiation conditions, nanofiber-expanded HUHSCs were able to undergo neural differentiation in vitro, as determined by gene and protein expression of neural markers such as MAP2, NeuN, HuC, GFAP and Oligo2. Thirty days after a single intracardioventricular injection of HUHSCs to MPTP-mice there was a significant recovery of tyrosine hydroxylase (TH) immunostaining in CPu. There was an increase in the size and staining density of TH+ cells in SNc, while their number was unchanged.