Prenatal transplantation of mesenchymal stem cells to treat osteogenesis imperfecta

Maternal and fetal safety outcomes after in utero stem cell injection: A systematic review

OBJECTIVE

To investigate the maternal and fetal safety of In utero stem cell transplantation (IUSCT).

METHODS

Medline®, Embase and Cochrane library (1967-2023) search for publications reporting IUSCT in humans. Two reviewers independently screened abstracts and full-text papers.

RESULTS

Sixty six transplantation procedures in 52 fetuses were performed for haemoglobinopathies (n = 14), red cell/bleeding disorders (n = 4), immunodeficiencies (n = 15), storage disorders (n = 7), osteogenesis imperfecta (n = 2) and healthy fetuses (n = 10). The average gestational age was 18.9 weeks; of procedures reporting the injection route, cells were delivered by intraperitoneal (n = 37), intravenous (n = 19), or intracardiac (n = 4) injection or a combination (n = 3); most fetuses received one injection (n = 41). Haematopoietic (n = 40) or mesenchymal (n = 12) stem cells were delivered. The cell dose was inconsistently reported (range 1.8-3.3 × 109 cells total (n = 27); 2.7-5.0 × 109 /kg estimated fetal weight (n = 17)). The acute fetal procedural complication rate was 4.5% (3/66); the acute fetal mortality rate was 3.0% (2/66). Neonatal survival was 69.2% (36/52). Immediate maternal and pregnancy outcomes were reported in only 30.8% (16/52) and 44.2% (23/52) of cases respectively. Four fetal/pregnancy outcomes would also classify as ≥ Grade 2 maternal adverse events.

CONCLUSIONS

Short-, medium-, and long-term maternal and fetal adverse events should be reported in all IUSCT studies.

Mesenchymal stem cells in the treatment of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a disease caused by mutations in different genes resulting in mild, severe, or lethal forms. With no cure, researchers have investigated the use of cell therapy to correct the underlying molecular defects of OI. Mesenchymal stem cells (MSCs) are of particular interest because of their differentiation capacity, immunomodulatory effects, and their ability to migrate to sites of damage. MSCs can be isolated from different sources, expanded in culture, and have been shown to be safe in numerous clinical applications. This review summarizes the preclinical and clinical studies of MSCs in the treatment of OI. Altogether, the culmination of these studies show that MSCs from different sources: 1) are safe to use in the clinic, 2) migrate to fracture sites and growth sites in bone, 3) engraft in low levels, 4) improve clinical outcome but have a transient effect, 5) have a therapeutic effect most likely due to paracrine mechanisms, and 6) have a reduced therapeutic potential when isolated from patients with OI.

Mesenchymal stromal cells in hematopoietic cell transplantation

Mesenchymal stromal cells (MSCs) are widely recognized to possess potent immunomodulatory activity, as well as to stimulate repair and regeneration of diseased or damaged tissue. These fundamental properties suggest important applications in hematopoietic cell transplantation. Although the mechanisms of therapeutic activity in vivo are yet to be fully elucidated, MSCs seem to suppress lymphocytes by paracrine mechanisms, including secreted mediators and metabolic modulators. Most recently, host macrophage engulfment of apoptotic MSCs has emerged as an important contributor to the immune suppressive microenvironment. Although bone marrow-derived MSCs are the most commonly studied, the tissue source of MSCs may be a critical determinant of immunomodulatory function. The key application of MSC therapy in hematopoietic cell transplantation is to prevent or treat graft-versus-host disease (GVHD). The pathogenesis of GVHD reveals multiple potential targets. Moreover, the recently proposed concept of tissue tolerance suggests a new possible mechanism of MSC therapy for GVHD. Beyond GVHD, MSCs may facilitate hematopoietic stem cell engraftment, which could gain greater importance with increasing use of haploidentical transplantation. Despite many challenges and much doubt, commercial MSC products for pediatric steroid-refractory GVHD have been licensed in Japan, conditionally licensed in Canada and New Zealand, and have been recommended for approval by an FDA Advisory Committee in the United States. Here, we review key historical data in the context of the most salient recent findings to present the current state of MSCs as adjunct cell therapy in hematopoietic cell transplantation.

Mesenchymal stem cells modifications for enhanced bone targeting and bone regeneration

In pathological bone conditions (e.g., osteoporotic fractures or critical size bone defects), increasing the pool of osteoblast progenitor cells is a promising therapeutic approach to facilitate bone healing. Since mesenchymal stem cells (MSCs) give rise to the osteogenic lineage, a number of clinical trials investigated the potential of MSCs transplantation for bone regeneration. However, the engraftment of transplanted cells is often hindered by insufficient oxygen and nutrients supply and the tendency of MSCs to home to different sites of the body. In this review, we discuss various approaches of MSCs transplantation for bone regeneration including scaffold and hydrogel constructs, genetic modifications and surface engineering of the cell membrane aimed to improve homing and increase cell viability, proliferation and differentiation.

αCGRP Affects BMSCs' Migration and Osteogenesis via the Hippo-YAP Pathway

Alpha-calcitonin gene-related peptide (αCGRP) plays a significant pathophysiological role in the regulation of bone metabolism. Our previous research indicated that αCGRP might have a potential application in enhancing osseointegration in vivo. To further uncover the intrinsic mechanism of its networks in bone regeneration, here we investigate the impact of αCGRP on osteogenic differentiation in bone marrow-derived mesenchymal stem cells (BMSCs) from both wild-type and αCGRP^-/- mice. Considering the half-life of αCGRP in plasma is only 10 min, we applied αCGRP lentivirus and stably transfected it into BMSCs, followed by transfection identification and cell cycle assay. We further conducted a series of in vitro tests, and the results revealed that biological functions including migratory ability and osteogenicity exhibited positive correlation with BMSCs' αCGRP expression. Meanwhile, this phenomenon was associated with an enhanced expression of YAP (Yes-associated protein), the key downstream effector of the Hippo pathway. To sum up, our data together with previous in vivo observations is likely to elucidate the intrinsic mechanism of αCGRP in bone remodeling, and αCGRP would appear to be a novel treatment to promote bone wound healing.

Enhancement of Mesenchymal Stem Cell-Driven Bone Regeneration by Resveratrol-Mediated SOX2 Regulation

Mesenchymal stem cells (MSCs) are an attractive cell source for regenerative medicine. However, MSCs age rapidly during long-term ex vivo culture and lose their therapeutic potential before they reach effective cell doses (ECD) for cell therapy. Thus, a prerequisite for effective MSC therapy is the development of cell culture methods to preserve the therapeutic potential during long-term ex vivo cultivation. Resveratrol (RSV) has been highlighted as a therapeutic candidate for bone disease. Although RSV treatment has beneficial effects on bone-forming cells, in vivo studies are lacking. The current study showed that long-term (6 weeks from primary culture date)-cultured MSCs with RSV induction retained their proliferative and differentiation potential despite reaching ECD. The mechanism of RSV action depends entirely on the SIRT1-SOX2 axis in MSC culture. In a rat calvarial defect model, RSV induction significantly improved bone regeneration after MSC transplantation. This study demonstrated an example of efficient MSC therapy for treating bone defects by providing a new strategy using the plant polyphenol RSV.

In Utero Transplantation of Expanded Autologous Amniotic Fluid Stem Cells Results in Long-Term Hematopoietic Engraftment

In utero transplantation (IUT) of hematopoietic stem cells (HSCs) has been proposed as a strategy for the prenatal treatment of congenital hematological diseases. However, levels of long‐term hematopoietic engraftment achieved in experimental IUT to date are subtherapeutic, likely due to host fetal HSCs outcompeting their bone marrow (BM)‐derived donor equivalents for space in the hematopoietic compartment. In the present study, we demonstrate that amniotic fluid stem cells (AFSCs; c‐Kit+/Lin−) have hematopoietic characteristics and, thanks to their fetal origin, favorable proliferation kinetics in vitro and in vivo, which are maintained when the cells are expanded. IUT of autologous/congenic freshly isolated or cultured AFSCs resulted in stable multilineage hematopoietic engraftment, far higher to that achieved with BM‐HSCs. Intravascular IUT of allogenic AFSCs was not successful as recently reported after intraperitoneal IUT. Herein, we demonstrated that this likely due to a failure of timely homing of donor cells to the host fetal thymus resulted in lack of tolerance induction and rejection. This study reveals that intravascular IUT leads to a remarkable hematopoietic engraftment of AFSCs in the setting of autologous/congenic IUT, and confirms the requirement for induction of central tolerance for allogenic IUT to be successful. Autologous, gene‐engineered, and in vitro expanded AFSCs could be used as a stem cell/gene therapy platform for the in utero treatment of inherited disorders of hematopoiesis. stem cells2019;37:1176–1188

Current and Emerging Therapeutic Options for the Management of Rare Skeletal Diseases

Increasing knowledge in the field of rare diseases has led to new therapeutic approaches in the last decade. Treatment strategies have been developed after elucidation of the underlying genetic alterations and pathophysiology of certain diseases (e.g., in osteogenesis imperfecta, achondroplasia, hypophosphatemic rickets, hypophosphatasia and fibrodysplasia ossificans progressiva). Most of the drugs developed are specifically designed agents interacting with the disease-specific cascade of enzymes and proteins involved. While some are approved (asfotase alfa, burosumab), others are currently being investigated in phase III trials (denosumab, vosoritide, palovarotene). To offer a multi-disciplinary therapeutic approach, it is recommended that patients with rare skeletal disorders are treated and monitored in highly specialized centers. This guarantees the greatest safety for the individual patient and offers the possibility of collecting data to further improve treatment strategies for these rare conditions. Additionally, new therapeutic options could be achieved through increased awareness, not only in the field of pediatrics but also in prenatal and obstetric specialties. Presenting new therapeutic options might influence families in their decision of whether or not to terminate a pregnancy with a child with a skeletal disease.

Bone Marrow Transplantation for Treatment of the Col1a2+/G610C Osteogenesis Imperfecta Mouse Model

Bone marrow transplantation (BMT) of healthy donor cells has been postulated as a strategy for treating osteogenesis imperfecta (OI) and other bone fragility disorders. The effect of engraftment by tail vein injection and/or marrow ablation by 6 Gy whole body irradiation were tested in Col1a2^+/G610C (OI) mice as a model of mild-moderate OI. Dual-emission X-ray absorptiometry, microCT, and 4-point bending were used to measure bone volume (BV), bone mineral density (BMD), and biomechanical strength. BV, BMD, and mechanical strength were reduced in OI mice compared to wild type (WT) controls. BMT with and without irradiation yielded no difference in BV and BMD outcomes for both OI and WT mice, at 3 weeks. Transplantation of OI cells into OI mice to test for paracrine effects of BMT also showed no difference with non-transplanted OI mice. In a parallel cell tracking study, donor marrow was taken from transgenic mice constitutively expressing tdTomato and transplanted into WT mice. Lineage tracking demonstrated that irradiation considerably enhanced engraftment of tdTomato+ cells. However, tdTomato+ cells predominantly expressed TRAP and not AP, indicating engrafted donor cells were chiefly from the hematopoietic lineages. These data show that whole marrow transplantation fails to rescue the bone phenotype of Col1a2^+/G610C (OI) mice and that osteopoietic engraftment is not significantly enhanced by irradiation. These findings are highly relevant to modern approaches focused on the gene repair of patient cells ex vivo and their subsequent reintroduction into the osteopoietic compartment via the circulation.

In Utero Transplantation of Placenta-Derived Mesenchymal Stromal Cells for Potential Fetal Treatment of Hemophilia A

Hemophilia A (HA) is an X-linked recessive disorder caused by mutations in the factor VIII (FVIII) gene leading to deficient blood coagulation. The current standard of care is frequent infusions of plasma-derived FVIII or recombinant B-domain-deleted FVIII (BDD-FVIII). While this treatment is effective, many patients eventually develop FVIII inhibitors that limit the effectiveness of the infused FVIII. As a monogenic disorder, HA is an ideal target for gene or cell-based therapy. Several studies have investigated allogeneic stem cell therapy targeting in utero or postnatal treatment of HA but have not been successful in completely correcting HA. Autologous in utero transplantation of mesenchymal stem cells is promising for treatment of HA due to the naive immune status of the fetal environment as well as its potential to prevent transplant rejection and long-term FVIII inhibitor formation. HA can be diagnosed by chorionic villus sampling performed during the first trimester (10 to 13 wk) of gestation. In this study, we used an established protocol and isolated placenta-derived mesenchymal stromal cells (PMSCs) from first trimester chorionic villus tissue and transduced them with lentiviral vector encoding the BDD-FVIII gene. We show that gene-modified PMSCs maintain their immunophenotype and multipotency, express, and secrete high levels of active FVIII. PMSCs were then transplanted at embryonic day 14.5 (E14.5) into wild-type fetuses from time-mated pregnant mice. Four days after birth, pups were checked for engraftment, and varying levels of expression of human green fluorescent protein were found in the organs tested. This study shows feasibility of the approach to obtain PMSCs from first trimester chorionic villus tissue, genetically modify them with the FVIII gene, and transplant them in utero for cell-mediated gene therapy of HA. Future studies will involve evaluation of long-term engraftment, phenotypic correction in HA mice, and prevention of FVIII inhibitor development by this approach.

Receptor activity-modifying protein 1 regulates the phenotypic expression of BMSCs via the Hippo/Yap pathway

Receptor activity-modifying protein 1 (RAMP1) might be a critical regulator during bone wound healing. However, the roles and mechanisms of RAMP1 in osteogenesis remain unclear. Here, we aimed to elucidate the role of RAMP1 and explore the effects of Yes-associated protein 1 (Yap1), an effector of the Hippo/Yap pathway, in this process. We used a RAMP1 overexpression lentiviral system in bone marrow mesenchymal stem cells (BMSCs), which enhanced RAMP1 expression in an effective, appropriate, and sustained manner. Alkaline phosphatase (ALP) activity assays and alizarin red staining showed that RAMP1 promoted osteogenic differentiation of BMSCs after calcitonin gene-related peptide (CGRP) treatment (10 ^-8  mol/L). Moreover, real-time polymerase chain reaction and Western blot analysis indicated that RAMP1 upregulated the expression of osteogenic phenotypic markers (ALP, runt-related transcription factor 2, osteopontin; p < 0.05). To further uncover the mechanism of RAMP1 in osteogenic differentiation, we used verteporfin (10 ^-7  mol/L) to block Yap1. Notably, verteporfin impaired RAMP1-induced osteogenesis. Taken together, our findings confirmed that RAMP1 is a key mediator of bone regeneration and indicate that RAMP1 promotes CGRP-induced osteogenic differentiation of BMSCs via regulation of the Hippo/Yap pathway.

Whole Exome Sequencing: Applications in Prenatal Genetics

Prenatal whole exome sequencing (WES) has the potential to increase the ability to provide more diagnostic capabilities in fetuses with sonographic abnormalities, which would then improve the ability to counsel families. It is also often the first step in improving the path toward informed diagnosis and treatment, which is especially important in the era of advancing in utero fetal therapy. This article discusses the current literature regarding prenatal WES, clinical indications for WES, challenges with interpretation/counseling (variants of unknown significance), research priorities, ethical issues, and potential future advances.

Epiphyseal growth plate architecture is unaffected by early postnatal activation of the expression of R992C collagen II mutant

Spondyloepiphyseal dysplasia (SED) exemplifies a group of heritable diseases caused by mutations in collagenous proteins of the skeletal system. Its main feature is altered skeletal growth. Pathomechanisms of SED include: changes in the stability of collagen II molecules, inability to form proper collagen fibrils, excessive intracellular retention of mutant molecules, and endoplasmic reticulum stress. The complexity of this pathomechanism presents a challenge for designing therapies for SED. Our earlier research tested whether such therapies only succeed when applied during a limited window of development. Here, employing an inducible mouse model of SED caused by the R992C mutation in collagen II, we corroborate our earlier observations that a therapy must be applied at the prenatal or early postnatal stages of skeletal growth in order to be successful. Moreover, we demonstrate that blocking the expression of the R992C collagen II mutant at the early prenatal stages leads to long-term positive effects. Although, we could not precisely mark the start of the expression of the mutant, these effects are not significantly changed by switching on the mutant production at the early postnatal stages. By demonstrating the need for early therapeutic interventions, our study provides, for the first time, empirically-based directions for designing effective therapies for SED and, quite likely, for other skeletal dysplasias caused by mutations in key macromolecules of the skeletal system.

Minimally Invasive Fetal Surgery

Fetal surgery corrects severe congenital anomalies in utero to prevent their severe consequences on fetal development. The significant risk of open fetal operations to the pregnant mother has driven innovation toward minimally invasive procedures that decrease the risks inherent to hysterotomy. In this article, we discuss the basic principles of minimally invasive fetal surgery, the general history of its development, specific conditions and procedures used to treat them, and the future of the field.

Rare genetic diseases: update on diagnosis, treatment and online resources

Rare genetic diseases collectively impact a significant portion of the world's population. For many diseases there is limited information available, and clinicians can find difficulty in differentiating between clinically similar conditions. This leads to problems in genetic counseling and patient treatment. The biomedical market is affected because pharmaceutical and biotechnology industries do not see advantages in addressing rare disease treatments, or because the cost of the treatments is too high. By contrast, technological advances including DNA sequencing and analysis, together with computer-aided tools and online resources, are allowing a more thorough understanding of rare disorders. Here, we discuss how the collection of various types of information together with the use of new technologies is facilitating diagnosis and, consequently, treatment of rare diseases.

Extracellular vesicles released from mesenchymal stromal cells stimulate bone growth in osteogenesis imperfecta

BACKGROUND

Systemic infusion of mesenchymal stromal cells (MSCs) has been shown to induce acute acceleration of growth velocity in children with osteogenesis imperfecta (OI) despite minimal engraftment of infused MSCs in bones. Using an animal model of OI we have previously shown that MSC infusion stimulates chondrocyte proliferation in the growth plate and that this enhanced proliferation is also observed with infusion of MSC conditioned medium in lieu of MSCs, suggesting that bone growth is due to trophic effects of MSCs. Here we sought to identify the trophic factor secreted by MSCs that mediates this therapeutic activity.

METHODS

To examine whether extracellular vesicles (EVs) released from MSCs have therapeutic activity, EVs were isolated from MSC conditioned medium by ultracentrifugation. To further characterize the trophic factor, RNA or microRNA (miRNA) within EVs was depleted by either ribonuclease (RNase) treatment or suppressing miRNA biogenesis in MSCs. The functional activity of these modified EVs was evaluated using an in vitro chondrocyte proliferation assay. Finally, bone growth was evaluated in an animal model of OI treated with EVs.

RESULTS

We found that infusion of MSC-derived EVs stimulated chondrocyte proliferation in the growth plate, resulting in improved bone growth in a mouse model of OI. However, infusion of neither RNase-treated EVs nor miRNA-depleted EVs enhanced chondrocyte proliferation.

CONCLUSION

MSCs exert therapeutic effects in OI by secreting EVs containing miRNA, and EV therapy has the potential to become a novel cell-free therapy for OI that will overcome some of the current limitations in MSC therapy.

Osteopetroses, emphasizing potential approaches to treatment

Osteopetroses are a heterogeneous group of rare genetic bone diseases sharing the common hallmarks of reduced osteoclast activity, increased bone mass and high bone fragility. Osteoclasts are bone resorbing cells that contribute to bone growth and renewal through the erosion of the mineralized matrix. Alongside the bone forming activity by osteoblasts, osteoclasts allow the skeleton to grow harmonically and maintain a healthy balance between bone resorption and formation. Osteoclast impairment in osteopetroses prevents bone renewal and deteriorates bone quality, causing atraumatic fractures. Osteopetroses vary in severity and are caused by mutations in a variety of genes involved in bone resorption or in osteoclastogenesis. Frequent signs and symptoms include osteosclerosis, deformity, dwarfism and narrowing of the bony canals, including the nerve foramina, leading to hematological and neural failures. The disease is autosomal, with only one extremely rare form associated so far to the X-chromosome, and can have either recessive or dominant inheritance. Recessive ostepetroses are generally lethal in infancy or childhood, with a few milder forms clinically denominated intermediate osteopetroses. Dominant osteopetrosis is so far associated only with mutations in the CLCN7 gene and, although described as a benign form, it can be severely debilitating, although not at the same level as recessive forms, and can rarely result in reduced life expectancy. Severe osteopetroses due to osteoclast autonomous defects can be treated by Hematopoietic Stem Cell Transplant (HSCT), but those due to deficiency of the pro-osteoclastogenic cytokine, RANKL, are not suitable for this procedure. Likewise, it is unclear as to whether HSCT, which has high intrinsic risks, results in clinical improvement in autosomal dominant osteopetrosis. Therefore, there is an unmet medical need to identify new therapies and studies are currently in progress to test gene and cell therapies, small interfering RNA approach and novel pharmacologic treatments.

In Utero Stem Cell Transplantation: Potential Therapeutic Application for Muscle Diseases

Muscular dystrophies, myopathies, and traumatic muscle injury and loss encompass a large group of conditions that currently have no cure. Myoblast transplantations have been investigated as potential cures for these conditions for decades. However, current techniques lack the ability to generate cell numbers required to produce any therapeutic benefit. In utero stem cell transplantation into embryos has been studied for many years mainly in the context of hematopoietic cells and has shown to have experimental advantages and therapeutic applications. Moreover, patient-derived cells can be used for experimental transplantation into nonhuman animal embryos via in utero injection as the immune response is absent at such early stages of development. We therefore propose in utero transplantation as a potential method to generate patient-derived humanized skeletal muscle as well as muscle stem cells in animals for therapeutic purposes as well as patient-specific drug screening.

Skeletal Dysplasias: Growing Therapy for Growing Bones

Skeletal dysplasias represent a large and diverse group of rare conditions affecting collagen and bone. They can be clinically classified based on radiographic and physical features, and many can be further defined at a molecular level (Bonafe et al., 2015). Early diagnosis is critical to proper medical management including pharmacologic treatment when available. Patients with severe skeletal dysplasias often have small chests with respiratory insufficiency or airway obstruction and require immediate intubation after birth. Thereafter a variety of orthopedic, neurosurgical, pulmonary, otolaryngology interventions may be needed. In terms of definitive treatment for skeletal dysplasias, there are few pharmacotherapeutic options available for the majority of these conditions. We sought to describe therapies that are currently available or under investigation for skeletal dysplasias.

Prospects and limitations of improving skeletal growth in a mouse model of spondyloepiphyseal dysplasia caused by R992C (p.R1192C) substitution in collagen II

Skeletal dysplasias form a group of skeletal disorders caused by mutations in macromolecules of cartilage and bone. The severity of skeletal dysplasias ranges from precocious arthropathy to perinatal lethality. Although the pathomechanisms of these disorders are generally well defined, the feasibility of repairing established aberrant skeletal tissues that developed in the presence of mutant molecules is currently unknown. Here, we employed a validated mouse model of spondyloepiphyseal dysplasia (SED) that enables temporal control of the production of the R992C (p.R1192C) collagen II mutant that causes this disease. Although in our earlier studies we determined that blocking the expression of this mutant at the early prenatal stages prevents a SED phenotype, the utility of blocking the R992C collagen II at the postnatal stages is not known. Here, by switching off the expression of R992C collagen II at various postnatal stages of skeletal development, we determined that significant improvements of cartilage and bone morphology were achieved only when blocking the production of the mutant molecules was initiated in newborn mice. Our study indicates that future therapies of skeletal dysplasias may require defining a specific time window when interventions should be applied to be successful.

Osteogenic Differentiation in Healthy and Pathological Conditions

This review focuses on the osteogenic differentiation of mesenchymal stem cells (MSC), bone formation and turn-over in good and ill skeletal fates. The interacting molecular pathways which control bone remodeling in physiological conditions during a lifelong process are described. Then, alterations of the molecular pathways regulating osteogenesis are addressed. In the aging process, as well as in glucocorticoid-induced osteoporosis, bone loss is caused not only by an unbalanced bone resorption activity, but also by an impairment of MSCs’ commitment towards the osteogenic lineage, in favour of adipogenesis. Mutations affecting the expression of key genes involved in the control of bone development occur in several heritable bone disorders. A few examples are described in order to illustrate the pathological consequences of perturbation in different steps of osteogenic commitment, osteoblast maturation, and matrix mineralization, respectively. The involvement of abnormal MSC differentiation in cancer is then discussed. Finally, a brief overview of clinical applications of MSCs in bone regeneration and repair is presented.

Transcription factor ZNF25 is associated with osteoblast differentiation of human skeletal stem cells

Background

The differentiation of human bone marrow derived skeletal stem cells (known as human bone marrow stromal or mesenchymal stem cells, hMSCs) into osteoblasts involves the activation of a small number of well-described transcription factors. To identify additional osteoblastic transcription factors, we studied gene expression of hMSCs during ex vivo osteoblast differentiation.

Results

Clustering of gene expression, and literature investigation, revealed three transcription factors of interest – ZNF25, ZNF608 and ZBTB38. siRNA knockdown of ZNF25 resulted in significant suppression of alkaline phosphatase (ALP) activity. This effect was not present for ZNF608 and ZBTB38. To identify possible target genes of ZNF25, we analyzed gene expression following ZNF25 siRNA knockdown. This revealed a 23-fold upregulation of matrix metallopeptidase 1 and an 18-fold upregulation of leucine-rich repeat containing G protein-coupled receptor 5 and RAN-binding protein 3-like. We also observed enrichment in extracellular matrix organization, skeletal system development and regulation of ossification in the entire upregulated set of genes. Consistent with its function as a transcription factor during osteoblast differentiation of hMSC, we showed that the ZNF25 protein exhibits nuclear localization and is expressed in osteoblastic and osteocytic cells in vivo. ZNF25 is conserved in tetrapod vertebrates and contains a KRAB (Krueppel-associated box) transcriptional repressor domain.

Conclusions

This study shows that the uncharacterized transcription factor, ZNF25, is associated with differentiation of hMSC to osteoblasts.

[Calcitonin gene-related peptide-induced osteogenic differentiation of mouse bone marrow stromal cells through Hippo pathway in vitro]

OBJECTIVE

Previous studies have clarified that calcitonin gene-related peptide (CGRP) can promote the biologi- cal activity of osteoblasts. To further reveal the role of CGRP in bone repair, we studied its influence on osteogenic differentia- tion of mouse bone marrow stromal cells (BMSCs) and initially explored the effect of the Hippo signaling pathway with this process.

METHODS

BMSCs were induced to osteogenic differentiate osteoblasts by different concentrations of CGRP for a screening of the optimal concentration. CGRP was added in BMSCs, then the activity of alkaline phosphatase (ALP) and the number of mineralized nodules were examined by specific ALP kits after 48 hours and alizarin red staining fluid after 7 days, respectively. The protein expression of p-Mst1/2 was measured by Western blot. Verteporfin was used to block the downstream Yap signaling. The mRNA expression of collagen type I (Col I) and runt-related transcription factor 2 (Runx2) were detected by reverse transcription-polymerase chain reaction.

RESULTS

Compared to the blank group, different concentrations of CGRP (10⁻⁹, 10⁻⁸, 10⁻⁷ mol · L⁻¹), especially 10⁻⁸ mol · L⁻¹, significantly increased the ALP activity of BMSCs (P < 0.05). Alizarin red staining also showed more mineralized nodules in 10⁻⁸ mol · L⁻¹ group. The expression of p-Mst1/2 increased in the CGRP group (P < 0.05). Verteporfin treatment effectively decreased the mRNA expression of Runx2 and Col I (P < 0.05).

CONCLUSION

The Hippo signaling pathway plays a role in CGRP-induced osteogenic differentiation in mouse BMSCs.

In utero stem cell transplantation and gene therapy: Recent progress and the potential for clinical application

Advances in prenatal diagnosis have led to the prenatal management and treatment of a variety of congenital diseases. Although surgical treatment has been successfully applied to specific anatomic defects that place the fetus at a risk of death or life-long disability, the indications for fetal surgical intervention have remained relatively limited. By contrast, prenatal stem cell and gene therapy await clinical application, but they have tremendous potential to treat a broad range of genetic disorders. If there are biological advantages unique to fetal development that favor fetal stem cell or gene therapy over postnatal treatment, prenatal therapy may become the preferred approach to the treatment of any disease that can be prenatally diagnosed and cured by stem cell or gene therapy. Here, we review the field including recent progress toward clinical application and imminent clinical trials for cellular and gene therapy.