A quadripotential mesenchymal progenitor cell isolated from the marrow of an adult mouse

The Lower in Vivo Osteogenicity of Adipose Tissue-Derived Stem Cells Correlates with a Higher Innate Immune Response

Adipose tissue-derived mesenchymal stem cells (ATSCs) have been used as an alternative to bone marrow-derived mesenchymal stem cells (BMSCs) for bone tissue engineering applications. The ability of ATSCs to promote new bone formation remains lower than that of BMSCs. This study aimed to investigate the mechanisms underlying osteogenicity differences between human ATSCs and BMSCs in ceramic constructs, focusing on the effects of inflammation on this process. In contrast to ATSC-containing constructs, which did not induce bone formation in an ectopic mouse model, BMSC constructs consistently did so. Gene expression analysis revealed that human BMSCs, concomitantly with host murine progenitors, differentiated into the osteogenic lineage early post-implantation. In contrast, ATSCs differentiated later, when few implanted viable cells remained post-implantation, while the host murine cells did not differentiate. Comparison of the inflammatory profile in the cell constructs indicated concomitant upregulation of some human and murine inflammatory genes in the ATSC-constructs compared to the BMSC-constructs during the first-week post-implantation. The high level of chemokine production by the ATSCs was confirmed at the gene and protein levels before implantation. The immune cell recruitment within the constructs was then explored post-implantation. Higher numbers of TRAP-/ MRC1 (CD206) + multinucleated giant cells, NOS2 + M1, and ARG1 + M2 macrophages were present in the ATSC constructs than in the BMSC constructs. These results proved that ATSCs are a transient source of inflammatory cytokines promoting a transient immune response post-implantation; this milieu correlates with impaired osteogenic differentiation of both the implanted ATSCs and the host osteoprogenitor cells.

Review of Caplan (1991) on cell-based therapeutic technology using Mesenchymal Stem Cells

This classic discusses the original 1991 publication 'Mesenchymal Stem Cells (MSCs)' by Dr. Caplan on the emergence of a new therapeutic technology of self-cell repair using MSCs. After the original classic publication, a large number of methods to regenerate injured tissue have been reported. Currently, MSCs are used clinically to repair articular cartilage defects, liver cirrhosis, cerebral infarction, spinal cord injury, graft-versus-host disease and others. As a result, MSCs are considered one of the most important cell sources for regenerative medicine. An MSC has been demonstrated to be a multipotent stem cell in cell culture and was thought to contribute to the regeneration of injured tissue at transplant sites, but recently, the concept of MSCs has changed such that they are now referred to as "medicinal signaling cells," owing to their often indirect effects on tissue repair and regeneration. Regardless of the name, either mesenchymal stem cells or medicinal signaling cells, MSCs will be used to regenerate injured tissue more widely in the near future.

Bone marrow mesenchymal stem cells' osteogenic potential: superiority or non-superiority to other sources of mesenchymal stem cells?

Skeletal problems are an increasing issue due to the increase in the global aging population. Different statistics reports show that today, the global population is aging that results in skeletal problems, increased health system costs, and even higher mortality associated with skeletal problems. Common treatments such as surgery and bone grafts are not always effective and in some cases, they can even cause secondary problems such as infections or improper repair. Cell therapy is a method that can be utilized along with common treatments independently. Mesenchymal stem cells (MSCs) are a very important and efficient source in terms of different diseases, especially bone problems. These cells are present in different tissues such as bone marrow, adipose tissue, umbilical cord, placenta, dental pulp, peripheral blood, amniotic fluid and others. Among the types of MSCs, bone marrow mesenchymal stem cells (BMMSCs) are the most widely used source of these cells, which have appeared to be very effective and promising in terms of skeletal diseases, especially compared to the other sources of MSCs. This study focuses on the specific potential and content of BMMSCs from which the specific capacity of these cells originates, and compares their osteogenic potential with other types of MSCs, and also the future directions in the application of BMMSCs as a source for cell therapy.

Neural crest cells give rise to non-myogenic mesenchymal tissue in the adult murid ear pinna

Despite being a major target of reconstructive surgery, development of the external ear pinna remains poorly studied. As a craniofacial organ highly accessible to manipulation and highly conserved among mammals, the ear pinna represents a valuable model for the study of appendage development and wound healing in the craniofacial complex. Here we provide a cellular characterization of late gestational and postnatal ear pinna development in Mus musculus and Acomys cahirinus and demonstrate that ear pinna development is largely conserved between these species. Using Wnt1-cre;ROSAmT/mG mice we find that connective tissue fibroblasts, elastic cartilage, dermal papilla cells, dermal sheath cells, vasculature, and adipocytes in the adult pinna are derived from cranial crest. In contrast, we find that skeletal muscle and hair follicles are not derived from neural crest cells. Cellular analysis using the naturally occurring short ear mouse mutant shows that elastic cartilage does not develop properly in distal pinna due to impaired chondroprogenitor proliferation. Interestingly, while chondroprogenitors develop in a mostly continuous sheet, the boundaries of cartilage loss in the short ear mutant strongly correlate with locations of vasculature-conveying foramen. Concomitant with loss of elastic cartilage we report increased numbers of adipocytes, but this seems to be a state acquired in adulthood rather than a developmental abnormality. In addition, chondrogenesis remains impaired in the adult mid-distal ear pinna of these mutants. Together these data establish a developmental basis for the study of the ear pinna with intriguing insights into the development of elastic cartilage.

The miRNA-144-5p/IRS1/AKT axis regulates the migration, proliferation, and mineralization of osteoblasts: A mechanism of bone repair in diabetic osteoporosis

Diabetic osteoporosis (DOP) is a disorder of bone metabolism induced by multiple mechanisms. Previous studies have revealed that microRNAs (miRNAs) play crucial roles in bone metabolism. MiRNA-144-5p has been proven to participate in the regulation of osteoblast activities; however, its specific mechanism in DOP has not been elucidated. This study investigated whether high glucose (HG) inhibited osteoblasts by regulating miRNA-144-5p. Our results showed that HG inhibited bone formation not only in vivo but also in vitro. We observed that HG severely hindered the migration, proliferation and mineralization of osteoblasts, while miRNA-144-5p was upregulated by way of the cell counting kit-8 assay, wound healing assay, alkaline phosphatase (ALP) activity assay and alizarin red staining. Double luciferase reporter experiments showed that miRNA-144-5p directly targeted insulin receptor substrate 1 (IRS1). The IRS1/AKT signaling pathway is closely related to osteoblasts' migration, proliferation, and mineralization. Silencing miRNA-144-5p promoted the mRNA, and protein expression of IRS1, thereby letting the expression of total AKT down, and then preventing phosphorylation of AKT into the nucleus to regulate migration, proliferation, and mineralization genes of osteoblasts. In conclusion, this study indicated that HG regulated the migration, proliferation, and mineralization of osteoblasts via the miRNA-144-5p/IRS1/AKT axis, which suggested a possible mechanism for DOP pathology.

Intravenous Transplantation of Human Hair Follicle-Derived Mesenchymal Stem Cells Ameliorates Trabecular Bone Loss in Osteoporotic Mice

Background: Hair follicles harbor a rich autologous stem cell pool and human hair follicle-derived mesenchymal stem cells (hHF-MSCs) have multi-lineage differentiation potential. Many sources of MSCs include hHF-MSCs have been attractive candidates for cell therapy, regenerative medicine and tissue engineering. The present study is to explore the effect of intravenous transplantation of hHF-MSCs on bone mass in osteoporotic mice and its mechanism, and provides prospects for clinical applications for the treatment of osteoporosis with hHF-MSCs.

Methods: Physically pull out about 20 hairs with intact hair follicles from the occipital area of the scalp of healthy volunteers, and extract hair follicle-derived fibroblast-like cells. These cells were cultured and characterized in vitro. Intravenous injection of hHF-MSCs was performed on ovariectomy-induced and age-related osteoporotic SCID mice for osteoporosis treatment. The mice were sacrificed 7 weeks after the second injection and samples were collected. The long bones and L1 vertebrae were collected for micro-CT scan, histomorphometry and immunohistochemical analysis. Peripheral serum were collected for ELISA analysis and antibody array.

Results: Hair follicle-derived fibroblast-like cells were defined as hHF-MSCs. Intravenous transplantation of hHF-MSCs can better restores trabecular bone mass in osteoporotic mice. The double calcein labeling assay, trap staining of bones and ELISA analysis in peripheral serum showed enhanced bone formation and weakened bone resorption after transplantation. Antibody array and immunohistochemical analysis showed that several cytokines including OPG, Wnt2b, Noggin, VCAM-1 and RANKL might be involved in this process.

Conclusion: Human HF-MSCs transplantation can combat trabecular bone loss induced by menopause and aging in mice. And the above mechanism that hHF-MSCs transplantation inhibits bone resorption and promote bone formation is related to OPG, Wnt2b, VCAM-1, Noggin and RANKL.

Natural Polymeric Scaffolds for Tissue Engineering Applications

Natural polymeric scaffolds can be used for tissue engineering applications such as cell delivery and cell-free supporting of native tissues. This is because of their desirable properties such as; high biocompatibility, tunable mechanical strength and conductivity, large surface area, porous- and extracellular matrix (ECM)-mimicked structures. Specifically, their less toxicity and biocompatibility makes them suitable for several tissue engineering applications. For these reasons, several biopolymeric scaffolds are currently being explored for numerous tissue engineering applications. To date, research on the nature, chemistry, and properties of nanocomposite biopolymers are been reported, while the need for a comprehensive research note on more tissue engineering application of these biopolymers remains. As a result, this present study comprehensively reviews the development of common natural biopolymers as scaffolds for tissue engineering applications such as cartilage tissue engineering, cornea repairs, osteochondral defect repairs, and nerve regeneration. More so, the implications of research findings for further studies are presented, while the impact of research advances on future research and other specific recommendations are added as well.

Local insulin application has a dose-dependent effect on lumbar fusion in a rabbit model

The purpose of this study was to determine if locally applied insulin has a dose-responsive effect on posterolateral lumbar fusion. Adult male New Zealand White rabbits underwent posterolateral intertransverse spinal fusions (PLFs) at L5-L6 using suboptimal amounts of autograft. Fusion sites were treated with collagen sponge soaked in saline (control, n = 11), or with insulin at low (5 or 10 units, n = 13), mid (20 units, n = 11), and high (40 units, n = 11) doses. Rabbits were euthanized at 6 weeks. The L5-L6 spine segment underwent manual palpation and radiographic evaluation performed by two fellowship trained spine surgeons blinded to treatment. Differences between groups were evaluated by analysis of variance on ranks followed by post-hoc Dunn's tests. Forty-three rabbits were euthanized at the planned 6 weeks endpoint, while three died or were euthanized prior to the endpoint. Radiographic evaluation found bilateral solid fusion in 10%, 31%, 60%, and 60% of the rabbits from the control and low, mid, and high-dose insulin-treated groups, respectively (p < 0.05). As per manual palpation, 7 of 10 rabbits in the mid-dose insulin group were fused as compared to 1 of 10 rabbits in the control group (p < 0.05). This study demonstrates that insulin enhanced the effectiveness of autograft to increase fusion success in the rabbit PLF model. The study indicates that insulin or insulin-mimetic compounds can be used to promote bone regeneration.

MSCs-engineered biomimetic PMAA nanomedicines for multiple bioimaging-guided and photothermal-enhanced radiotherapy of NSCLC

Background

The recently developed biomimetic strategy is one of the mostly effective strategies for improving the theranostic efficacy of diverse nanomedicines, because nanoparticles coated with cell membranes can disguise as “self”, evade the surveillance of the immune system, and accumulate to the tumor sites actively.

Results

Herein, we utilized mesenchymal stem cell memabranes (MSCs) to coat polymethacrylic acid (PMAA) nanoparticles loaded with Fe(III) and cypate—an derivative of indocyanine green to fabricate Cyp-PMAA-Fe@MSCs, which featured high stability, desirable tumor-accumulation and intriguing photothermal conversion efficiency both in vitro and in vivo for the treatment of lung cancer. After intravenous administration of Cyp-PMAA-Fe@MSCs and Cyp-PMAA-Fe@RBCs (RBCs, red blood cell membranes) separately into tumor-bearing mice, the fluorescence signal in the MSCs group was 21% stronger than that in the RBCs group at the tumor sites in an in vivo fluorescence imaging system. Correspondingly, the T₁-weighted magnetic resonance imaging (MRI) signal at the tumor site decreased 30% after intravenous injection of Cyp-PMAA-Fe@MSCs. Importantly, the constructed Cyp-PMAA-Fe@MSCs exhibited strong photothermal hyperthermia effect both in vitro and in vivo when exposed to 808 nm laser irradiation, thus it could be used for photothermal therapy. Furthermore, tumors on mice treated with phototermal therapy and radiotherapy shrank 32% more than those treated with only radiotherapy.

Conclusions

These results proved that Cyp-PMAA-Fe@MSCs could realize fluorescence/MRI bimodal imaging, while be used in phototermal-therapy-enhanced radiotherapy, providing desirable nanoplatforms for tumor diagnosis and precise treatment of non-small cell lung cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00823-6.

PIP5k1β controls bone homeostasis through modulating both osteoclast and osteoblast differentiation

PIP5k1β is crucial to the generation of phosphotidylinosotol (4, 5)P2. PIP5k1β participates in numerous cellular activities, such as B cell and platelet activation, cell phagocytosis and endocytosis, cell apoptosis, and cytoskeletal organization. In the present work, we aimed to examine the function of PIP5k1β in osteoclastogenesis and osteogenesis to provide promising strategies for osteoporosis prevention and treatment. We discovered that PIP5k1β deletion in mice resulted in obvious bone loss and that PIP5k1β was highly expressed during both osteoclast and osteoblast differentiation. Deletion of the gene was found to enhance the proliferation and migration of bone marrow-derived macrophage-like cells to promote osteoclast differentiation. PIP5k1β-/- osteoclasts exhibited normal cytoskeleton architecture but stronger resorption activity. PIP5k1β deficiency also promoted activation of mitogen-activated kinase and Akt signaling, enhanced TRAF6 and c-Fos expression, facilitated the expression and nuclear translocation of NFATC1, and upregulated Grb2 expression, thereby accelerating osteoclast differentiation and function. Finally, PIP5k1β enhanced osteoblast differentiation by upregulating master gene expression through triggering smad1/5/8 signaling. Therefore, PIP5k1β modulates bone homeostasis and remodeling.

Evaluating the effect of transplanting umbilical cord matrix stem cells on ischemic tolerance in an animal model of stroke

OBJECTIVE

Stroke, a cerebrovascular disease, has been introduced as the second cause of death and physical disability in the world. Recently, cell-based therapy has been considered by the scientific community as a promising strategy for reducing ischemic damages. The stem cells of the umbilical cord release growth and neurotrophic factors. The remarkable properties of these cells are the reason why they were selected as a potential candidate in the present research.

METHODS

In this study, the impact of transplanting umbilical cord stem cells on injuries resulting from ischemia was investigated. The male rats were categorized into three major. Using stereotaxic surgery, stem cells were injected to the right striatum of the brain. One week after transplantation, cerebral ischemic induction surgery was performed. The rats in the transplantation + ischemia group were separately divided into distinct sub-groups to explore the score of the neurological deficits, infarction volume, integrity of the blood-brain barrier, and brain edema.

RESULTS

In this study, a significant decrease was observed in the neurological deficits of the transplantation + ischemia group compared with those of the control group. Similarly, the volume of infarction, the permeability of the blood-brain barrier, and edema were significantly reduced in the transplantation + ischemia group in comparison with those of the control group.

CONCLUSION

The pretreatment of the transplanted umbilical cord stem cells in the striatum of ischemic rats possibly leads to restorative events, exerting a decreasing effect on cell death. Subsequently, these events may improve the motor ability and reduce ischemic injuries.

Lessons from joint development for cartilage repair in the clinic

More than 250 years ago, William Hunter stated that when cartilage is destroyed it never recovers. In the last 20 years, the understanding of the mechanisms that lead to joint formation and the knowledge that some of these mechanisms are reactivated in the homeostatic responses of cartilage to injury has offered an unprecedented therapeutic opportunity to achieve cartilage regeneration. Very large investments in ambitious clinical trials are finally revealing that, although we do not have perfect medicines yet, disease modification is a feasible possibility for human osteoarthritis.

Ark shell protein-derived bioactive peptides promote osteoblastic differentiation through upregulation of the canonical Wnt/β-catenin signaling in human bone marrow-derived mesenchymal stem cells

In this study, the stimulating effect of ark shell protein-derived peptides AWLNH and PHDL on osteoblast differentiation in human bone marrow-derived mesenchymal stem cells (hBMMSCs) and its molecular mechanism was investigated. The hBMMSCs were cultured with two peptides and osteogenic markers were analyzed. Results showed that enhanced ALP activity and calcification were detected in the presence of AWLNH and PHDL. Based on western blotting, RT-qPCR, and immunostaining analysis, AWLNH and PHDL are specific for osteoblast differentiation of hBMMSCs through activating the canonical Wnt/β-catenin signaling pathway followed by activating Runx2, osterix, and type I collagen. Loss-of-function assay with DKK-1, a Wnt antagonist, showed that the canonical Wnt/β-catenin signaling was essential for AWLNH and PHDL-induced osteogenesis in hBMMSCs. These findings suggested that AWLNH and PHDL can stimulate osteoblast differentiation of hBMMSCs via upregulating the canonical Wnt/β-catenin signaling and may be useful for a potential nutraceuticals or pharmaceuticals to treat osteoporosis. PRACTICAL APPLICATIONS: Ark shell is a popular foodstuff in Korea. However, biological effects of its protein and peptide have not been explored in many ways. This study demonstrated that ark shell protein-derived peptides promoted osteoblast differentiation in hBMMSCs through upregulating the canonical Wnt/β-catenin signaling. The results of this study could be a basis to promote its application as functional foods and/or nutraceuticals.

Stem Cells in Veterinary Medicine-Current State and Treatment Options

Regenerative medicine is a branch of medicine that develops methods to grow, repair, or replace damaged or diseased cells, organs or tissues. It has gained significant momentum in recent years. Stem cells are undifferentiated cells with the capability to self—renew and differentiate into tissue cells with specialized functions. Stem cell therapies are therefore used to overcome the body's inability to regenerate damaged tissues and metabolic processes after acute or chronic insult. The concept of stem cell therapy was first introduced in 1991 by Caplan, who proposed that massive differentiation of cells into the desired tissue could be achieved by isolation, cultivation, and expansion of stem cells in in vitro conditions. Among different stem cell types, mesenchymal stem cells (MSC) currently seem to be the most suitable for therapeutic purposes, based on their simple isolation and culturing techniques, and lack of ethical issues regarding their usage. Because of their remarkable immunomodulatory abilities, MSCs are increasingly gaining recognition in veterinary medicine. Developments are primarily driven by the limitations of current treatment options for various medical problems in different animal species. MSCs represent a possible therapeutic option for many animal diseases, such as orthopedic, orodental and digestive tract diseases, liver, renal, cardiac, respiratory, neuromuscular, dermal, olfactory, and reproductive system diseases. Although we are progressively gaining an understanding of MSC behavior and their mechanisms of action, some of the issues considering their use for therapy are yet to be resolved. The aim of this review is first to summarize the current knowledge and stress out major issues in stem cell based therapies in veterinary medicine and, secondly, to present results of clinical usage of stem cells in veterinary patients.

Multifunctional nanoparticles in stem cell therapy for cellular treating of kidney and liver diseases

The review gives an overview of the mechanisms of internalization and distribution of nanoparticles in stem cells this is achieved via providing analysis of the methods used in exploring the migration routes of stem cells, and their reciprocity. In addition, exploring microenvironment target in the body, and tracking the fate of exogenously transplanted stem cells by using innovative and non-invasive techniques will also be discussed. Such techniques like magnetic resonance imaging (MRI), multimodality tracking, optical imaging, and nuclear medicine imaging, which were designed to follow up stem cell migration. This review will explain the various distinctive strategies to enhance homing of labeled stem cells with nanoparticles into damaged hepatic and renal tissues, this purpose was obtained by inducing a specific gene into stem cells, various chemokines, and applying an external magnetic field. Also, this work illustrates how to improve nanoparticles uptake by using transfection agents or covalently binding an exogenous protein (i.e., Human immunodeficiency virus-Tat protein) or conjugating a receptor-specific monoclonal antibody or make modifications to iron coat. It contains stem cell labeling methods such as extracellular labeling and internalization approaches. Ultimately, our review indicates trails of researchers in nanoparticles utilization in stem cell therapy in both kidney and liver diseases.

Bone Marrow-Derived Mesenchymal Stem Cell Potential Regression of Dysplasia Associating Experimental Liver Fibrosis in Albino Rats

Objectives

Assessing the therapeutic efficacy of superparamagnetic iron oxide nanoparticles (SPIO) labeled bone marrow-derived mesenchymal stem cells (BM-MSCs) on experimental liver fibrosis and associated dysplasia.

Materials and Methods

MSCs were obtained from 10 male Sprague-Dawley rats while 50 female rats were divided into control (CG), liver fibrosis (CCL4, intraperitoneal injection of CCl₄ for 8 weeks), and CCL₄ rats treated with SPIO-labeled MSCs (MSCs/CCl₄) with and without continuing CCL₄ injection for another 8 weeks. Assessment included liver histopathology, liver function tests, transmission electron microscopic tracing for homing of SPIO-MSCs, immunofluorescence histochemistry for fibrosis and dysplasia markers (transforming growth factor-beta (TGF-β1), proliferation nuclear antigen (PCNA), glypican 3)), and quantitative gene expression analysis for matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1).

Results

SPIO-labeled MSCs were engrafted in the fibrotic liver and the BM/MSCs demonstrated regression for fibrous tissue deposition and inhibition progression of dysplastic changes in the liver of CCl₄-treated rats on both the histological and molecular levels.

Conclusion

BM-MSCs possess regenerative and antidysplastic potentials.

There Is No "Stem Cell Mess"

IMPACT STATEMENT

The impact should encourage continued research and clinical trials using mesenchymal stem cells.

Engineered Mesenchymal Stem Cells for Targeting Solid Tumors: Therapeutic Potential beyond Regenerative Therapy

Mesenchymal stem cells (MSCs) have previously demonstrated considerable promise in regenerative medicine based on their ability to proliferate and differentiate into cells of different lineages. More recently, there has been a significant interest in using MSCs as cellular vehicles for targeted cancer therapy by exploiting their tumor homing properties. Initial studies focused on using genetically modified MSCs for targeted delivery of various proapoptotic, antiangiogenic, and therapeutic proteins to a wide variety of tumors. However, their use as drug delivery vehicles has been limited by poor drug load capacity. This review discusses various strategies for the nongenetic modification of MSCs that allows their use in tumor-targeted delivery of small molecule chemotherapeutic agents. SIGNIFICANCE STATEMENT: There has been considerable interest in exploiting the tumor homing potential of MSCs to develop them as a vehicle for the targeted delivery of cytotoxic agents to tumor tissue. The inherent tumor-tropic and drug-resistant properties make MSCs ideal carriers for toxic payload. While significant progress has been made in the area of the genetic modification of MSCs, studies focused on identification of molecular mechanisms that contribute to the tumor tropism along with optimization of the engineering conditions can further improve their effectiveness as drug delivery vehicles.

Long-term culture of mesenchymal stem cells impairs ATM-dependent recognition of DNA breaks and increases genetic instability

BACKGROUND

Mesenchymal stem cells (MSCs) are attracting increasing interest for cell-based therapies, making use of both their immuno-modulating and regenerative potential. For such therapeutic applications, a massive in vitro expansion of donor cells is usually necessary to furnish sufficient material for transplantation. It is not established to what extent the long-term genomic stability and potency of MSCs can be compromised as a result of this rapid ex vivo expansion. In this study, we investigated the DNA damage response and chromosomal stability (indicated by micronuclei induction) after sub-lethal doses of gamma irradiation in murine MSCs at different stages of their in vitro expansion.

METHODS

Bone-marrow-derived tri-potent MSCs were explanted from 3-month-old female FVB/N mice and expanded in vitro for up to 12 weeks. DNA damage response and repair kinetics after gamma irradiation were quantified by the induction of γH2AX/53BP1 DSB repair foci. Micronuclei were counted in post-mitotic, binucleated cells using an automated image analyzer Metafer4. Involvement of DNA damage response pathways was tested using chemical ATM and DNA-PK inhibitors.

RESULTS

Murine bone-marrow-derived MSCs in long-term expansion culture gradually lose their ability to recognize endogenous and radiation-induced DNA double-strand breaks. This impaired DNA damage response, indicated by a decrease in the number of γH2AX/53BP1 DSB repair foci, was associated with reduced ATM dependency of foci formation, a slower DNA repair kinetics, and an increased number of residual DNA double-strand breaks 7 h post irradiation. In parallel with this impaired efficiency of DNA break recognition and repair in older MSCs, chromosomal instability after mitosis increased significantly as shown by a higher number of micronuclei, both spontaneously and induced by γ-irradiation. Multifactorial regression analysis demonstrates that in vitro aging reduced DNA damage recognition in MSCs after irradiation by a multiplicative interaction with dose (p < 0.0001), whereas the increased frequency of micronuclei was caused by an additive interaction between in vitro aging and radiation dose.

CONCLUSION

The detrimental impact of long-term in vitro expansion on DNA damage response of MSCs warrants a regular monitoring of this process during the ex vivo growth of these cells to improve therapeutic safety and efficiency.

Isolation and characterization of turkey bone marrow-derived mesenchymal stem cells

Flexor tendon injury is often associated with suboptimal outcomes and results in substantial digit dysfunction. Stem cells have been isolated from several experimental animals for the growing interest and needs of utilizing cell-based therapies. Recently, turkey has been developed as a new large animal model for flexor tendon research. In the present study, we reported the isolation and characterization of bone marrow-derived mesenchymal stem cells (BMSCs) from 8- to 12-month-old heritage-breed turkeys. The isolated cells demonstrated fibroblast-like morphology, clonogenic capacity, and high proliferation rate. These cells were positive for surface antigens CD90, CD105, and CD44, but were negative for CD45. The multipotency of turkey BMSCs was determined by differentiating cells into osteogenic, adipogenic, chondrogenic, and tenogenic lineages. There was upregulated gene expression of tenogenic markers, including mohawk, tenomodulin, and EGR1 as well as increased collagen synthesis in BMP12 induced cells. The successful isolation and verification of bone marrow-derived MSCs from turkey would provide opportunities of studying cell-based therapies and developing new treatments for tendon injuries using this novel preclinical large animal model. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1419-1428, 2019.

Silk fibroin induces chondrogenic differentiation of canine adipose-derived multipotent mesenchymal stromal cells/mesenchymal stem cells

Under appropriate culture conditions, mesenchymal stem cells (MSC), also called more properly multipotent mesenchymal stromal cells (MMSC), can be induced toward differentiation into different cell lineages. In order to guide stem cell fate within an environment resembling the stem cell niche, different biomaterials are being developed. In the present study, we used silk fibroin (SF) as a biomaterial supporting the growth of MMSC and studied its effect on chondrogenesis of canine adipose–derived MMSC (cADMMSC). Adipose tissue was collected from nine privately owned dogs. MMSC were cultured on SF films and SF scaffolds in a standard cell culture medium. Cell morphology was evaluated by scanning electron microscopy (SEM). Chondrogenic differentiation was evaluated by alcian blue staining and mRNA expression of collagen type 1, collagen type 2, Sox9, and Aggrecan genes. cADMMSC cultured on SF films and SF scaffolds stained positive using alcian blue. SEM images revealed nodule-like structures with matrix vesicles and fibers resembling chondrogenic nodules. Gene expression of chondrogenic markers Sox9 and Aggrecan were statistically significantly upregulated in cADMMSC cultured on SF films in comparison to negative control cADMMSC. This result suggests that chondrogenesis of cADMMSC could occur when cells were grown on SF films in a standard cell culture medium without specific culture conditions, which were previously considered necessary for induction of chondrogenic differentiation.

Dental Pulp Tissue Engineering Using Mesenchymal Stem Cells: a Review with a Protocol

Mesenchymal stem cells (MSCs) are adult stem cells that can be isolated from human and animal sources such as rats. Recently, an in vivo protocol for pulp tissue engineering using implantation of bone marrow MSCs into rat pulpotomized molars was established by our research group. This coronal pulp regeneration model showed almost complete regeneration/healing with dentin bridge formation when the cavity was sealed with mineral trioxide aggregate (MTA) to create a biocompatible seal of the pulp. This method is a powerful tool for elucidating the processes of dental pulp tissue regeneration following implantation of MSCs. In the present review, we discuss the literature in the field of dental pulp tissue engineering using MSCs including dental pulp stem cells and stem cells from exfoliated deciduous teeth. In addition, we present a brief step-by-step protocol of the coronal pulp regeneration model focusing on the implantation of rat bone marrow MSCs, biodegradable scaffolds, and hydrogels in pulpotomized rat molars. The protocol may lay the foundation for studies aiming at defining further histological and molecular mechanism of the rat pulp tissue engineering.

Enhanced articular cartilage regeneration with SIRT1-activated MSCs using gelatin-based hydrogel

To investigate the functional effects of resveratrol (RSV) on mesenchymal stem cells (MSCs), we treated MSCs with RSV continuously during ex vivo expansion. MSCs were continuously treated with RSV from passage (P) 0 to P5. A proliferative capacity of RSV-treated MSCs was higher than that of non-treated MSCs and similar with P1-MSCs. Continuous treatment of RSV on MSCs increased the stemness and inhibited the senescence. During chondrogenic differentiation in vitro, RSV-treated MSCs had higher differentiation potential and reduced hypertrophic maturation, which are limitations for hyaline cartilage formation. The histological analysis of micromass demonstrated increased chondrogenic differentiation potential. We further explored the therapeutic effectiveness of this method in a rabbit osteochondral defect model. A rabbit osteochondral defect model was established to investigate the hyaline cartilage regeneration potential of RSV-treated MSCs. Moreover, the cartilage regeneration potential of RSV-treated MSCs was greater than that of untreated MSCs. The expression levels of chondrogenic markers increased and those of hypertrophic markers decreased in RSV-treated MSCs compared with untreated MSCs. Sustained treatment of RSV on MSCs during ex vivo expansion resulted in the maintenance of stemness and enhanced chondrogenic differentiation potential. Consequentially, highly efficient MSCs promoted superior hyaline cartilage regeneration in vivo. This novel treatment method provides a basis for cell-based tissue engineering.

Current status and potential challenges of mesenchymal stem cell-based therapy for malignant gliomas

Glioma, which accounts for more than 30% of primary central nervous system tumours, is characterised by symptoms such as headaches, epilepsy, and blurred vision. Glioblastoma multiforme is the most aggressive, malignant, and lethal brain tumour in adults. Even with progressive combination treatment with surgery, radiotherapy, and chemotherapy, the prognosis for glioma patients is still extremely poor. Compared with the poor outcome and slowly developing technologies for surgery and radiotherapy, the application of targeted chemotherapy with a new mechanism has become a research focus in this field.

Moreover, targeted therapy is promising for most solid tumours. The tumour-tropic ability of stem cells, including neural stem cells and mesenchymal stem cells, provides an alternative therapeutic approach. Thus, mesenchymal stem cell-based therapy is based on a tumour-selective capacity and has been thought to be an effective anti-tumour option over the past decades. An increasing number of basic studies on mesenchymal stem cell-based therapy for gliomas has yielded complex outcomes.

In this review, we summarise the biological characteristics of human mesenchymal stem cells, and the current status and potential challenges of mesenchymal stem cell-based therapy in patients with malignant gliomas.

miR-193a inhibits osteogenic differentiation of bone marrow-derived stroma cell via targeting HMGB1

BACKGROUND

miR-193a has been shown to be involved in a variety of biological processes, including cell proliferation, differentiation, and apoptosis. However, little is known about how miR-193a regulates osteogenic differentiation.

METHODS

We employed RT-qPCR to determine the level of miR-193a and mRNA level of HMGB1 and osteoblast-specific markers (Runx2, ALP, OSX, OCN). Besides, westernblot was used to probe protein level of phosphorylated MAPK family members and β-catenin. Bioinformatic analysis was used to predict the putative binding sequence of miR-193a to the 3'-UTR of HMGB1 and we confirmed this result by dual luciferase reporter assay. Alizarin red staining assay (ARS) and alkaline phosphatase activity (ALP) were performed to detect osteogenic differentiation.

RESULTS

miR-193a was downregulated in OM (osteogenic medium)induced hBMSC. More interestingly, we found that miR-193a mimic attenuated matrix mineralization and alkaline phosphatase activity, whereas miR-193a inhibitor exerted the opposite phenotypes. Mechanistically, we observed that miR-193a played an inhibitory role in expression of osteoblast-specific markers and activation of MAPK and Wnt signaling pathways. Bioinformatic analysis and dual luciferase assay demonstrated that miR-193a directly targeted 3'-UTR of HMGB1. Furthermore, we overexpressed HMGB1 in miR-193a overexpressed hBMSC to establish that HMGB1 acted as downstream target of miR-193a-inhibited osteogenic differentiation.

CONCLUSIONS

Here, we reveal miR-193a plays a suppressive role in osteogenic differentiation of hBMSC via targeting HMGB1. These findings provide a novel mechanism underlying osteogenic differentiation and offer therapeutical strategy for bone formation.

Bone regeneration with adipose derived stem cells in a rabbit model

It has been shown that stem cells are able to calcify both in vitro and in vivo once implanted under the skin, if conveniently differentiated. Nowadays, however, a study on their efficiency in osseous regeneration does not exist in scientific literature and this very task is the real aim of the present experimentation. Five different defects of 6 mm in diameter and 2 mm in depth were created in the calvaria of 8 white New Zealand rabbits. Four defects were regenerated using 2 different conveniently modified scaffolds (Bio-Oss® Block and Bio-Oss Collagen®, Geistlich), with and without the aid of stem cells. After the insertion, the part was covered with a collagen membrane fixed by 5 modified titan pins (Altapin®). The defect in the front was left empty on purpose as an internal control to each animal. Two animals were sacrificed respectively after 2, 4, 6, 10 weeks. The samples were evaluated with micro-CT and histological analysis. Micro-CT analysis revealed that the quantity of new bone for samples with Bio-Oss® Block and stem cells was higher than for samples with Bio-Oss® Block alone. Histological analysis showed that regeneration occurred in an optimal way in every sample treated with scaffolds. The findings indicated that the use of adult stem cells combined with scaffolds accelerated some steps in normal osseous regeneration.

Evaluation of Peripheral Blood and Cord Blood Platelet Lysates in Isolation and Expansion of Multipotent Mesenchymal Stromal Cells

Abstract: Background: Multipotent Mesenchymal Stromal Cells (MSCs) are used in tissue engineering and regenerative medicine. The in vitro isolation and expansion of MSCs involve the use of foetal bovine serum (FBS). However, many concerns have been raised regarding the safety of this product. In this study, alternative additives derived either from peripheral or cord blood were tested as an FBS replacement. Methods: Platelet lysates (PL) from peripheral and cord blood were used for the expansion of MSCs. The levels of growth factors in peripheral blood (PB) and cord blood (CB) PLs were determined using the Multiple Reaction Monitoring (MRM). Finally, the cell doubling time (CDT), tri-lineage differentiation and phenotypic characterization of the MSCs expanded with FBS and PLs were determined. Results: MSCs treated with culture media containing FBS and PB-PL, were successfully isolated and expanded, whereas MSCs treated with CB-PL could not be maintained in culture. Furthermore, the MRM analysis yielded differences in growth factor levels between PB-PL and CB-PL. In addition, the MSCs were successfully expanded with FBS and PB-PL and exhibited tri-lineage differentiation and stable phenotypic characteristics. Conclusion: PB-PL could be used as an alternative additive for the production of MSCs culture medium applied to xenogeneic-free expansion and maintenance of MSCs in large scale clinical studies.

Isolation of equine peripheral blood stem cells from a Japanese native horse

The sizes of Japanese native horses have drastically decreased, and protection of these populations is important for Japanese horse culture. Social trials as well as scientific attempts are necessary for maintaining the breed. Mesenchymal stem cells (MSCs) have potential as a cell source for various cell therapies. However, there have been no reports on MSCs of Japanese native horses. We aimed to isolate and characterize MSCs from a Japanese native horse, the Noma horse. Plastic-adherent and self-replicating cells were isolated from a Noma horse’s peripheral blood (PB). The isolated cells had trilineage potential and a surface antigen of mesenchymal cells, so they fulfilled the minimal criteria of MSCs. Therefore, PB can be one source of MSCs for Japanese native horses.

Isolation, cultivation, and characterization of human mesenchymal stem cells

Mesenchymal stem cells (MSC) exhibit a high self-renewal capacity, multilineage differentiation potential and immunomodulatory properties. This set of exceptional features makes them an attractive tool for research and clinical application. However, MSC are far from being a uniform cell type, which makes standardization difficult. The exact properties of human MSC (hMSC) can vary greatly depending on multiple parameters including tissue source, isolation method and medium composition. In this review we address the most important influence factors. We highlight variations in the differentiation potential of MSC from different tissue sources. Furthermore, we compare enzymatic isolation strategies with explants cultures focusing on adipose tissue and umbilical cords as two relevant examples. Additionally, we address effects of medium composition and serum supplementation on MSC expansion and differentiation. The lack of standardized methods for hMSC isolation and cultivation mandates careful evaluation of different protocols regarding efficiency and cell quality. MSC characterization based on a set of minimal criteria defined by the International Society for Cellular Therapy is a widely accepted practice, and additional testing for MSC functionality can provide valuable supplementary information. The MSC secretome has been identified as an important signaling mechanism to affect other cells. In this context, extracellular vesicles (EVs) are attracting increasing interest. The thorough characterization of MSC-derived EVs and their interaction with target cells is a crucial step toward a more complete understanding of MSC-derived EV functionality. Here, we focus on flow cytometric approaches to characterize free as well as cell bound EVs and address potential differences in the bioactivity of EVs derived from stem cells from different sources. © 2017 International Society for Advancement of Cytometry.

In-vitro characterization of canine multipotent stromal cells isolated from synovium, bone marrow, and adipose tissue: a donor-matched comparative study

Background

The dog represents an excellent large animal model for translational cell-based studies. Importantly, the properties of canine multipotent stromal cells (cMSCs) and the ideal tissue source for specific translational studies have yet to be established. The aim of this study was to characterize cMSCs derived from synovium, bone marrow, and adipose tissue using a donor-matched study design and a comprehensive series of in-vitro characterization, differentiation, and immunomodulation assays.

Methods

Canine MSCs were isolated from five dogs with cranial cruciate ligament rupture. All 15 cMSC preparations were evaluated using colony forming unit (CFU) assays, flow cytometry analysis, RT-PCR for pluripotency-associated genes, proliferation assays, trilineage differentiation assays, and immunomodulation assays. Data were reported as mean ± standard deviation and compared using repeated-measures analysis of variance and Tukey post-hoc test. Significance was established at p < 0.05.

Results

All tissue samples produced plastic adherent, spindle-shaped preparations of cMSCs. Cells were negative for CD34, CD45, and STRO-1 and positive for CD9, CD44, and CD90, whereas the degree to which cells were positive for CD105 was variable depending on tissue of origin. Cells were positive for the pluripotency-associated genes NANOG, OCT4, and SOX2. Accounting for donor and tissue sources, there were significant differences in CFU potential, rate of proliferation, trilineage differentiation, and immunomodulatory response. Synovium and marrow cMSCs exhibited superior early osteogenic activity, but when assessing late-stage osteogenesis no significant differences were detected. Interestingly, bone morphogenic protein-2 (BMP-2) supplementation was necessary for early-stage and late-stage osteogenic differentiation, a finding consistent with other canine studies. Additionally, synovium and adipose cMSCs proliferated more rapidly, displayed higher CFU potential, and formed larger aggregates in chondrogenic assays, although proteoglycan and collagen type II staining were subjectively decreased in adipose pellets as compared to synovial and marrow pellets. Lastly, cMSCs derived from all three tissue sources modulated murine macrophage TNF-α and IL-6 levels in a lipopolysaccharide-stimulated coculture assay.

Conclusions

While cMSCs from synovium, marrow, and adipose tissue share a number of similarities, important differences in proliferation and trilineage differentiation exist and should be considered when selecting cMSCs for translational studies. These results and associated methods will prove useful for future translational studies involving the canine model.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0639-6) contains supplementary material, which is available to authorized users.

Macrophage-Associated Osteoactivin/GPNMB Mediates Mesenchymal Stem Cell Survival, Proliferation, and Migration Via a CD44-Dependent Mechanism

Although MSCs have been widely recognized to have therapeutic potential in the repair of injured or diseased tissues, it remains unclear how functional activities of mesenchymal stem cells (MSCs) are influenced by the surrounding inflammatory milieu at the site of tissue injury. Macrophages constitute an essential component of innate immunity and have been shown to exhibit a phenotypic plasticity in response to various stimuli, which play a central role in both acute inflammation and wound repair. Osteoactivin (OA)/Glycoprotein non-metastatic melanoma protein B (GPNMB), a transmembrane glycoprotein that plays a role in cell differentiation, survival, and angiogenesis. The objective of this study was to investigate the potential role of OA/GPNMB in macrophage-induced MSC function. We found that reparative M2 macrophages express significantly greater levels of OA/GPNMB than pro-inflammatory M1 macrophages. Furthermore, using loss of function and rescue studies, we demonstrated that M2 macrophages-secreted OA/GPNMB positively regulates the viability, proliferation, and migration of MSCs. More importantly, we demonstrated that OA/GPNMB acts through ERK and AKT signaling pathways in MSCs via CD44, to induce these effects. Taken together, our results provide pivotal insight into the mechanism by which OA/GPNMB contributes to the tissue reparative phenotype of M2 macrophages and positively regulates functional activities of MSCs. J. Cell. Biochem. 117: 1511-1521, 2016. © 2015 Wiley Periodicals, Inc.

Control of dental-derived induced pluripotent stem cells through modified surfaces for dental application

OBJECTIVE

The aim of this study is to investigate the behaviour of iPSc derived from dental stem cells in terms of initial adhesion, differentiation potential on differently surface-treated titanium disc.

MATERIALS AND METHODS

iPSc derived from human gingival fibroblasts (hGFs) were established using 4-reprogramming factors transduction with Sendai virus. The hGF-iPSc established in this study exhibited the morphology and growth properties similar to human embryonic stem (ES) cells and expressed pluripotency makers. Alkaline Phosphatase (AP) staining, Embryoid Body (EB) formation and in vitro differentiation and karyotyping further confirmed pluripotency of hGF-iPSc. Then, hGF-iPSc were cultured on machined- and Sandblasted and acid etched (SLA)-treated titanium discs with osteogenic induction medium and their morphological as well as quantitative changes according to different surface types were investigated using Alizrin Red S staining, Scanning electron microscopy (SEM), Flow cytometry and RT-PCR.

RESULTS

Time-dependent and surface-dependent morphological changes as well as quantitative change in osteogenic differentiation of hGF-iPSc were identified and osteogenic gene expression of hGF-iPSc cultured on SLA-treated titanium disc found to be greater than machined titanium disc, suggesting the fate of hGF-iPSc may be determined by the characteristics of surface to which hGF-iPSc first adhere.

CONCLUSIONS

iPSc derived from dental stem cell can be one of the most promising and practical cell sources for personalized regenerative dentistry and their morphological change as well as quantitative change in osteogenic differentiation according to different surface types may be further utilized for future clinical application incorporated with dental implant.

Isolation and characterization of equine dental pulp stem cells derived from Thoroughbred wolf teeth

Mesenchymal stem cells (MSCs) are adult multipotent stem cells that are capable of self-renewal and differentiation into multiple cell lineages. Methods for cell therapy using MSCs have been developed in equine medicine. Recently, human dental pulp stem cells (DPSCs) have drawn much attention owing to their trophic factor producing ability and minimally invasive collection methods. However, there have been no reports on equine dental pulp-derived cells (eDPCs). Therefore, the aim of this study was to isolate and characterize the eDPCs from discarded wolf teeth. Plastic-adherent spindle-shaped cells were isolated from wolf teeth. The doubling time of the isolated eDPCs was approximately 1 day. Differentiation assays using induction medium eDPCs differentiated into osteogenic, chondrogenic and adipogenic lineages. The eDPCs expressed mesenchymal makers (CD11a/18, CD44, CD90 CD105 and MHC class I and II), but did not express hematopoietic markers (CD34 and CD45). Taken together, the results show that eDPCs can be isolated from discarded wolf teeth, and they satisfy the minimal criteria for MSCs. Thus, these eDPCs can be referred to as equine DPSCs (eDPSCs). These eDPSCs may become a new source for cell therapy.

[Wnt/β-catenin signaling is involved in the Icariin induced proliferation of bone marrow mesenchymal stem cells]

OBJECTIVE

To investigate the effect of icariin on proliferation of bone marrow mesenchymal stem cells (BMSCs) in Sprague-Dawley (SD) rats.

METHODS

BMSCs were obtained from SD rat bone marrow with differential time adherent method. Its characteristic was identified through differentiation cell surface antigens and the multi-lineage (osteo/adipo/chondo) differentiation potential. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and 5-Bromo-2-Deoxyuridine (BrdU) incorporation were applied to detect the effect of icariin on BMSCs proliferation. Flow cytometry was used to detect proliferation index of BMSCs. The RNA level and the distribution of β-catenin were evaluated by Real-time Polymerase Chain Reaction (PCR) and Immunofluorescent staining respectively. Western blot was used to detect protein expression levels of β-catenin, glycogen synthase kinase-3 beta (GSK-3β), phospho-glycogen synthase kinase-3 beta (pGSK-3β) and cyclinD1.

RESULTS

Icariin promoted BMSCs proliferation at the concentration of 0.05-2.0 mg/L. The percentage of BrdU positive cells of BMSCs was increased from 40.98% to 70.42%, and the proliferation index value was increased from 8.9% to 17.5% with the treatment of 0.05 mg/L icariin, which significance values were both less than 0.05. Compared with the control group, total and nuclear β-catenin proteins, as well as β-catenin mRNA expression, were all increased with icariin treatment. Meanwhile, the phosphorylation level of GSK-3β and cyclinD1 protein expressions were also increased in BMSCs with icariin treatment.

CONCLUSION

The findings of the present study demonstrated that low dosage of icariin could promote BMSCs proliferation. The activation of Wnt/β-catenin pathways was involved in this process.

Rebuilding the Damaged Heart: Mesenchymal Stem Cells, Cell-Based Therapy, and Engineered Heart Tissue

Mesenchymal stem cells (MSCs) are broadly distributed cells that retain postnatal capacity for self-renewal and multilineage differentiation. MSCs evade immune detection, secrete an array of anti-inflammatory and anti-fibrotic mediators, and very importantly activate resident precursors. These properties form the basis for the strategy of clinical application of cell-based therapeutics for inflammatory and fibrotic conditions. In cardiovascular medicine, administration of autologous or allogeneic MSCs in patients with ischemic and nonischemic cardiomyopathy holds significant promise. Numerous preclinical studies of ischemic and nonischemic cardiomyopathy employing MSC-based therapy have demonstrated that the properties of reducing fibrosis, stimulating angiogenesis, and cardiomyogenesis have led to improvements in the structure and function of remodeled ventricles. Further attempts have been made to augment MSCs' effects through genetic modification and cell preconditioning. Progression of MSC therapy to early clinical trials has supported their role in improving cardiac structure and function, functional capacity, and patient quality of life. Emerging data have supported larger clinical trials that have been either completed or are currently underway. Mechanistically, MSC therapy is thought to benefit the heart by stimulating innate anti-fibrotic and regenerative responses. The mechanisms of action involve paracrine signaling, cell-cell interactions, and fusion with resident cells. Trans-differentiation of MSCs to bona fide cardiomyocytes and coronary vessels is also thought to occur, although at a nonphysiological level. Recently, MSC-based tissue engineering for cardiovascular disease has been examined with quite encouraging results. This review discusses MSCs from their basic biological characteristics to their role as a promising therapeutic strategy for clinical cardiovascular disease.

More Than Tiny Sacks: Stem Cell Exosomes as Cell-Free Modality for Cardiac Repair

Stem cell therapy provides immense hope for regenerating the pathological heart, yet has been marred by issues surrounding the effectiveness, unclear mechanisms, and survival of the donated cell population in the ischemic myocardial milieu. Poor survival and engraftment coupled to inadequate cardiac commitment of the adoptively transferred stem cells compromises the improvement in cardiac function. Various alternative approaches to enhance the efficacy of stem cell therapies and to overcome issues with cell therapy have been used with varied success. Cell-free components, such as exosomes enriched in proteins, messenger RNAs, and miRs characteristic of parental stem cells, represent a potential approach for treating cardiovascular diseases. Recently, exosomes from different kinds of stem cells have been effectively used to promote cardiac function in the pathological heart. The aim of this review is to summarize current research efforts on stem cell exosomes, including their potential benefits and limitations to develop a potentially viable therapy for cardiovascular problems.

Optimized Cryopreservation and Banking of Human Bone-Marrow Fragments and Stem Cells

Adult mesenchymal stem cells are a promising source for cell therapies and tissue engineering applications. Current procedures for banking of human bone-marrow mesenchymal stem cells (hBM-MSCs) require cell isolation and expansion, and thus the use of large amounts of animal sera. However, animal-derived culture supplements have the potential to trigger infections and severe immune reactions. The aim of this study was to investigate an optimized method for cryopreservation of human bone-marrow fragments for application in cell banking procedures where stem-cell expansion and use are not immediately needed. Whole trabecular fragments enclosing the bone marrow were stored in liquid nitrogen for 1 year in a cryoprotective solution containing a low concentration of dimethyl sulfoxide and a high concentration of human serum (HuS). After thawing, the isolation, colony-forming-unit ability, proliferation, morphology, stemness-related marker expression, cell senescence, apoptosis, and multi-lineage differentiation potential of hBM-MSCs were tested in media containing HuS compared with hBM-MSCs isolated from fresh fragments. Human BM-MSCs isolated from cryopreserved fragments expressed MSC markers until later passages, had a good proliferation rate, and exhibited the capacity to differentiate toward osteogenic, adipogenic, and myogenic lineages similar to hBM-MSCs isolated from fresh fragments. Moreover, the cryopreservation method did not induce cell senescence or cell death. These results imply that minimal processing may be adequate for the banking of tissue samples with no requirement for the immediate isolation and use of hBM-MSCs, thus limiting cost and the risk of contamination, and facilitating banking for clinical use. Furthermore, the use of HuS for cryopreservation and expansion/differentiation has the potential for clinical application in compliance with good manufacturing practice standards.

PTH Induces Systemically Administered Mesenchymal Stem Cells to Migrate to and Regenerate Spine Injuries. Mol Ther. 2016;24:318-330. [PMID: 26585691 DOI: 10.1038/mt.2015.211]

Osteoporosis affects more than 200 million people worldwide leading to more than 2 million fractures in the United States alone. Unfortunately, surgical treatment is limited in patients with low bone mass. Parathyroid hormone (PTH) was shown to induce fracture repair in animals by activating mesenchymal stem cells (MSCs). However, it would be less effective in patients with fewer and/or dysfunctional MSCs due to aging and comorbidities. To address this, we evaluated the efficacy of combination i.v. MSC and PTH therapy versus monotherapy and untreated controls, in a rat model of osteoporotic vertebral bone defects. The results demonstrated that combination therapy significantly increased new bone formation versus monotherapies and no treatment by 2 weeks (P < 0.05). Mechanistically, we found that PTH significantly enhanced MSC migration to the lumbar region, where the MSCs differentiated into bone-forming cells. Finally, we used allogeneic porcine MSCs and observed similar findings in a clinically relevant minipig model of vertebral defects. Collectively, these results demonstrate that in addition to its anabolic effects, PTH functions as an adjuvant to i.v. MSC therapy by enhancing migration to heal bone loss. This systemic approach could be attractive for various fragility fractures, especially using allogeneic cells that do not require invasive tissue harvest.

Mesenchymal stem cells: Identification, phenotypic characterization, biological properties and potential for regenerative medicine through biomaterial micro-engineering of their niche

Mesenchymal stem cells (MSCs) are multipotent stem cells. Although they were originally identified in bone marrow and described as 'marrow stromal cells', they have since been identified in many other anatomical locations in the body. MSCs can be isolated from bone marrow, adipose tissue, umbilical cord and other tissues but the richest tissue source of MSCs is fat. Since they are adherent to plastic, they may be expanded in vitro. MSCs have a distinct morphology and express a specific set of CD (cluster of differentiation) molecules. The phenotypic pattern for the identification of MSCs cells requires expression of CD73, CD90, and CD105 and lack of CD34, CD45, and HLA-DR antigens. Under appropriate micro-environmental conditions MSCs can proliferate and give rise to other cell types. Therefore, they are ideally suited for the treatment of systemic inflammatory and autoimmune conditions. They have also been implicated as key players in regenerating injured tissue following injury and trauma. MSC populations isolated from adipose tissue may also contain regulatory T (Treg) cells, which have the capacity for modulating the immune system. The immunoregulatory and regenerative properties of MSCs make them ideal for use as therapeutic agents in vivo. In this paper we review the literature on the identification, phenotypic characterization and biological properties of MSCs and discuss their potential for applications in cell therapy and regenerative medicine. We also discuss strategies for biomaterial micro-engineering of the stem cell niche.

Bottlenecks in the Efficient Use of Advanced Therapy Medicinal Products Based on Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) have been established as promising candidate sources of universal donor cells for cell therapy due to their contributions to tissue and organ homeostasis, repair, and support by self-renewal and multidifferentiation, as well as by their anti-inflammatory, antiproliferative, immunomodulatory, trophic, and proangiogenic properties. Various diseases have been treated by MSCs in animal models. Additionally, hundreds of clinical trials related to the potential benefits of MSCs are in progress. However, although all MSCs are considered suitable to exert these functions, dissimilarities have been found among MSCs derived from different tissues. The same levels of efficacy and desired outcomes have not always been achieved in the diverse studies that have been performed thus far. Moreover, autologous MSCs can be affected by the disease status of patients, compromising their use. Therefore, collecting information regarding the characteristics of MSCs obtained from different sources and the influence of the host (patient) medical conditions on MSCs is important for assuring the safety and efficacy of cell-based therapies. This review provides relevant information regarding factors to consider for the clinical application of MSCs.

Long-term expansion, enhanced chondrogenic potential, and suppression of endochondral ossification of adult human MSCs via WNT signaling modulation

Mesenchymal stem cells (MSCs) are a potential source of chondrogenic cells for the treatment of cartilage disorders, but loss of chondrogenic potential during in vitro expansion and the propensity of cartilage to undergo hypertrophic maturation impede their therapeutic application. Here we report that the signaling protein WNT3A, in combination with FGF2, supports long-term expansion of human bone marrow-derived MSCs. The cells retained their chondrogenic potential and other phenotypic and functional properties of multipotent MSCs, which were gradually lost in the absence of WNT3A. Moreover, we discovered that endogenous WNT signals are the main drivers of the hypertrophic maturation that follows chondrogenic differentiation. Inhibition of WNT signals during differentiation prevented calcification and maintained cartilage properties following implantation in a mouse model. By maintaining potency during expansion and preventing hypertrophic maturation following differentiation, the modulation of WNT signaling removes two major obstacles that impede the clinical application of MSCs in cartilage repair.

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WNT3A and FGF2 synergistically promote MSC proliferation

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WNT3A and FGF2 synergistically enhance MSC chondrogenic potential during expansion

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WNT3A and FGF2 maintain MSC characteristics over multiple passages

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In vitro WNT signaling modulation leads to stable cartilage formation in vivo

Mesenchymal Stem Cells: Rising Concerns over Their Application in Treatment of Type One Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder that leads to beta cell destruction and lowered insulin production. In recent years, stem cell therapies have opened up new horizons to treatment of diabetes mellitus. Among all kinds of stem cells, mesenchymal stem cells (MSCs) have been shown to be an interesting therapeutic option based on their immunomodulatory properties and differentiation potentials confirmed in various experimental and clinical trial studies. In this review, we discuss MSCs differential potentials in differentiation into insulin-producing cells (IPCs) from various sources and also have an overview on currently understood mechanisms through which MSCs exhibit their immunomodulatory effects. Other important issues that are provided in this review, due to their importance in the field of cell therapy, are genetic manipulations (as a new biotechnological method), routes of transplantation, combination of MSCs with other cell types, frequency of transplantation, and special considerations regarding diabetic patients' autologous MSCs transplantation. At the end, utilization of biomaterials either as encapsulation tools or as scaffolds to prevent immune rejection, preparation of tridimensional vascularized microenvironment, and completed or ongoing clinical trials using MSCs are discussed. Despite all unresolved concerns about clinical applications of MSCs, this group of stem cells still remains a promising therapeutic modality for treatment of diabetes.

Bone regeneration at dental implant sites with suspended stem cells

During the maintenance of bone marrow-derived mesenchymal stem cells (BMMSCs), suspended cells are discarded normally. We noted the osteogenic potential of these cells to be like that of anchorage-dependent BMMSCs. Therefore, we characterized suspended BMMSCs from rabbit bone marrow by bioengineering and applied the suspended BMMSCs to double-canaled dental implants inserted into rabbits. After primary isolation of BMMSCs, we collected the suspended cells during primary culture on the third day. The cells were transferred and maintained on an extracellular-matrix-coated culture plate. The cells were characterized and compared with BMMSCs by colony-forming-unit fibroblast (CFU-f) and cell proliferation assay, fluorescence-activated cell sorter (FACS), in vitro multipotency, and reverse transcription polymerase chain reaction (RT-PCR). We also analyzed the osteogenic potential of cells mixed with hydroxyapatite/tricalcium phosphate (HA/TCP) and transplanted into immunocompromised mice. We compared the viability and proliferation of the suspended BMMSCs and BMMSCs on the titanium implant surface and observed cell morphology. Then, the cells mixed with HA/TCP were applied to the double-canaled implants during installation into rabbit tibia. Four weeks later, we analyzed bone formation inside the canal by histomorphometry. The suspended cells showed higher CFU-f on the extracellular matrix (ECM)-coated culture plate and similar results of proliferation capacity compared with BMMSCs. The cells also showed osteogenic, adipogenic, and chondrogenic ability. The suspended cells showed levels of attachment survival and proliferation on the surfaces of titanium implant discs to be higher than or similar to those of BMMSCs. The suspended cells as well as BMMSCs showed stronger bone formation ability in both upper and lower canals of the implants compared with controls on double-canaled implants inserted into rabbit tibia. In this study, we showed that suspended cells after primary BMMSC isolation have bone regeneration capacity like that of BMMSCs, not only in vitro but also in vivo. ECM was valuable for propagation of MSCs for cell-based bone regeneration. Therefore, the suspended cells could also be useful tools for bone regeneration after implant surgery.