Mass production of early-stage bone-marrow-derived mesenchymal stem cells of rat using gelatin-coated matrix

Progress and emerging techniques for biomaterial-based derivation of mesenchymal stem cells (MSCs) from pluripotent stem cells (PSCs)

The use of mesenchymal stem cells (MSCs) for clinical purposes has skyrocketed in the past decade. Their multilineage differentiation potentials and immunomodulatory properties have facilitated the discovery of therapies for various illnesses. MSCs can be isolated from infant and adult tissue sources, which means they are easily available. However, this raises concerns because of the heterogeneity among the various MSC sources, which limits their effective use. Variabilities arise from donor- and tissue-specific differences, such as age, sex, and tissue source. Moreover, adult-sourced MSCs have limited proliferation potentials, which hinders their long-term therapeutic efficacy. These limitations of adult MSCs have prompted researchers to develop a new method for generating MSCs. Pluripotent stem cells (PSCs), such as embryonic stem cells and induced PSCs (iPSCs), can differentiate into various types of cells. Herein, a thorough review of the characteristics, functions, and clinical importance of MSCs is presented. The existing sources of MSCs, including adult- and infant-based sources, are compared. The most recent techniques for deriving MSCs from iPSCs, with a focus on biomaterial-assisted methods in both two- and three-dimensional culture systems, are listed and elaborated. Finally, several opportunities to develop improved methods for efficiently producing MSCs with the aim of advancing their various clinical applications are described.

Efficient hepatic differentiation and regeneration potential under xeno-free conditions using mass-producible amnion-derived mesenchymal stem cells

BACKGROUND

Amnion-derived mesenchymal stem cells (AM-MSCs) are an attractive source of stem cell therapy for patients with irreversible liver disease. However, there are obstacles to their use due to low efficiency and xeno-contamination for hepatic differentiation.

METHODS

We established an efficient protocol for differentiating AM-MSCs into hepatic progenitor cells (HPCs) by analyzing transcriptome-sequencing data. Furthermore, to generate the xeno-free conditioned differentiation protocol, we replaced fetal bovine serum (FBS) with polyvinyl alcohol (PVA). We investigated the hepatocyte functions with the expression of mRNA and protein, secretion of albumin, and activity of CYP3A4. Finally, to test the transplantable potential of HPCs, we transferred AM-MSCs along with hepatic progenitors after differentiated days 11, 12, and 13 based on the expression of hepatocyte-related genes and mitochondrial function. Further, we established a mouse model of acute liver failure using a thioacetamide (TAA) and cyclophosphamide monohydrate (CTX) and transplanted AM-HPCs in the mouse model through splenic injection.

RESULTS

We analyzed gene expression from RNA sequencing data in AM-MSCs and detected downregulation of hepatic development-associated genes including GATA6, KIT, AFP, c-MET, FGF2, EGF, and c-JUN, and upregulation of GSK3. Based on this result, we established an efficient hepatic differentiation protocol using the GSK3 inhibitor, CHIR99021. Replacing FBS with PVA resulted in improved differentiation ability, such as upregulation of hepatic maturation markers. The differentiated hepatocyte-like cells (HLCs) not only synthesized and secreted albumin, but also metabolized drugs by the CYP3A4 enzyme. The best time for translation of AM-HPCs was 12 days from the start of differentiation. When the AM-HPCs were transplanted into the liver failure mouse model, they settled in the damaged livers and differentiated into hepatocytes.

CONCLUSION

This study offers an efficient and xeno-free conditioned hepatic differentiation protocol and shows that AM-HPCs could be used as transplantable therapeutic materials. Thus, we suggest that AM-MSC-derived HPCs are promising cells for treating liver disease.

Polymer Cell Surface Coating Enhances Mesenchymal Stem Cell Retention and Cardiac Protection

Mesenchymal stem cell (MSC) therapy has been widely tested in clinical trials to promote healing post-myocardial infarction. However, low cell retention and the need for a large donor cell number in human studies remain a key challenge for clinical translation. Natural biomaterials such as gelatin are ideally suited as scaffolds to deliver and enhance cell engraftment after transplantation. A potential drawback of MSC encapsulation in the hydrogel is that the bulky matrix may limit their biological function and interaction with the surrounding tissue microenvironment that conveys important injury signals. To overcome this limitation, we adopted a gelatin methacrylate (gelMA) cell-coating technique that photocross-links gelatin on the individual cell surface at the nanoscale. The present study investigated the cardiac protection of gelMA coated, hypoxia preconditioned MSCs (gelMA-MSCs) in a murine myocardial infarction (MI) model. We demonstrate that the direct injection of gelMA-MSC results in significantly higher myocardial engraftment 7 days after MI compared to uncoated MSCs. GelMA-MSC further amplified MSC benefits resulting in enhanced cardioprotection as measured by cardiac function, scar size, and angiogenesis. Improved MSC cardiac retention also led to a greater cardiac immunomodulatory function after injury. Taken together, this study demonstrated the efficacy of gelMA-MSCs in treating cardiac injury with a promising potential to reduce the need for donor MSCs through enhanced myocardial engraftment.

Small RNA sequencing reveals a novel tsRNA-06018 playing an important role during adipogenic differentiation of hMSCs

Transfer RNA-derived small RNAs (tsRNAs), a novel type of non-coding RNA derivative, are able to regulate a wide range of biological processes. What role these tsRNAs play in the regulation of human bone marrow mesenchymal stem cell (hMSCs) adipogenic differentiation remains uncertain. We induced the adipogenic differentiation of human bone marrow mesenchymal cells (hMSCs) and then performed small RNA transcriptomic sequencing, leading us to identify tsRNA-06018 as a target of interest based upon resultant the tsRNA expression profiles. When tsRNA-06018 was knocked down, this led to the inhibition of adipogenesis and a decrease in adipogenic marker expression. When STC2 was overexpressed, this impaired the adipogenic differentiation of these cells. We further used luciferase reporter assays to confirm that tsRNA-06018 directly binds the 3'-untranslated region (3'-UTR) of STC2. In addition, we determined that both knocking down tsRNA-06018 and overexpressing STC2 increased extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation within cells. We also assessed that the adipogenic differentiation of hMSCs in which tsRNA-06018 was knocked down was further enhanced upon the addition of the ERK1/2 inhibitor U0126 as compared tsRNA-06018 knockdown alone. Taken together, using small RNA sequencing we profiled tsRNAs in hMSCs during the process of adipogenesis, leading us to identify tsRNA-06018 as a novel regulator of this differentiation process. This tsRNA was able to regulate adipogenic differentiation by targeting STC2 via the ERK1/2 signalling pathway.

A novel tsRNA-16902 regulating the adipogenic differentiation of human bone marrow mesenchymal stem cells

BACKGROUND

Transfer RNA-derived small RNAs (tsRNAs) are a recently discovered form of non-coding RNA capable of regulating myriad physiological processes. The role of tsRNAs in hMSC adipogenic differentiation, however, remains incompletely understood. The purpose of this study was to identify the novel tsRNA-16902 as a regulator of hMSC adipogenic differentiation.

METHODS

In this study, we conducted transcriptomic sequencing of hMSCs after inducing their adipogenic differentiation, and we were thereby able to clarify the molecular mechanism underlying the role of tsRNA-16902 in this context via a series of molecular biology methods.

RESULTS

When we knocked down tsRNA-16902 expression, this impaired hMSC adipogenic differentiation and associated marker gene expression. Bioinformatics analyses further revealed tsRNA-16902 to target retinoic acid receptor γ (RARγ). Luciferase reporter assays also confirmed the ability of tsRNA-16902 to bind to the RARγ 3'-untranslated region. Consistent with this, RARγ overexpression led to impaired hMSC adipogenesis. Further analyses revealed that Smad2/3 phosphorylation was increased in cells that either overexpressed RARγ or in which tsRNA-16902 had been knocked down. We also assessed the adipogenic differentiation of hMSCs in which tsRNA-16902 was knocked down and at the same time a Smad2/3 inhibitor was added to disrupt Smad2/3 phosphorylation. The adipogenic differentiation of hMSCs in which tsRNA-16902 was knocked down was further enhanced upon the addition of a Smad2/3 signaling inhibitor relative to tsRNA-16902 knockdown alone.

CONCLUSIONS

Through a comprehensive profiling analysis of tsRNAs that were differentially expressed in the context of hMSC adipogenic differentiation, we were able to identify tsRNA-16902 as a previously uncharacterized regulator of adipogenesis. tsRNA-16902 is able to regulate hMSC adipogenic differentiation by targeting RARγ via the Smad2/3 signaling pathway. Together, our results may thus highlight novel strategies of value for treating obesity.

Synergistic Adhesiveness of Fibronectin with PHSRN Peptide in Gelatin Mixture Promotes the Therapeutic Potential of Human ES-Derived MSCs

Introduction

Mesenchymal stem cells (MSCs) are promising candidates for cell therapy owing to their therapeutic effect in various diseases. In general, MSCs grow efficiently in serum-containing culture media, indicating an essential role of adhesion in their mesenchymal lineage-specific propagation. Nevertheless, the use of non-human supplements in culture (xeno-free issue) in addition to the lack of control over unknown factors in the serum hampers the clinical transition of MSCs.

Methods

In this study, embryonic stem cell derived mesenchymal stem cells (ES-MSCs) were used owing to their scalable production, and they expressed a series of MSC markers same as adipose-derived MSCs. The affinity of the culture matrix was increased by combining fibronectin coating with its adjuvant peptide, gelatin, or both (FNGP) on tissue culture polystyrene to compare the regenerative, therapeutic activities of ES-MSCs with a cell binding plate as a commercial control.

Results

The FNGP culture plate promoted pivotal therapeutic functions of ES-MSCs as evidenced by their increased stemness as well as anti-inflammatory and proangiogenic effects in vitro. Indeed, after culturing on the FNGP plates, ES-MSCs efficiently rescued the necrotic damages in mouse ischemic hindlimb model.

Conclusions

This study suggests a potential solution by promoting the surface affinity of culture plates using a mixture of human fibronectin and its adjuvant PHSRN peptide in gelatin. The FNGP plate is expected to serve as an effective alternative for serum-free MSC expansion for bench to clinical transition.

Mesenchymal Stem Cell Transplantation Promotes Functional Recovery through MMP2/STAT3 Related Astrogliosis after Spinal Cord Injury

Background and Objectives

Treatment with mesenchymal stem cells (MSC) in spinal cord injury (SCI) has been highlighted as therapeutic candidate for SCI. Although astrogliosis is a major phenomenon after SCI, the role of astrogliosis is still controversial. In this study, we determined whether acute transplantation of MSC improves the outcome of SCI through modulating astrogliosis.

Methods

Bone marrow derived rat MSCs were induced neural differentiation and transplanted after acute SCI rats. Matrix metalloproteinase (MMP) and neuro-inflammatory pathway were analyzed for acute astrogliosis at 1, 3 and 7 d after SCI in RT-PCR- and western blot analysis. Functional outcome was assessed serially at postoperative 1 d and weekly for 4 weeks. Histopathologic analysis was undertaken at 7 and 28 d following injury in immunohistochemistry.

Results

Transplantation of MSCs decreased IL-1α, CXCL-2, CXCL-10, TNF-α and TGF-β in a rat model of contusive SCI. Protein level of NF-κB p65 was slightly decreased while level of STAT-3 was increased. In immunohistochemistry, MSC transplantation increased acute astrogliosis whereas attenuated scar formation with increased sparing white matter of spinal cord lesions. In RT-PCR analysis, mRNA levels of MMP2 was significantly increased in MSC transplanted rats. In BBB locomotor scale, the rats of MSC treated group exhibited improvement of functional recovery.

Conclusions

Transplantation of MSC reduces the inflammatory reaction and modulates astrogliosis via MMP2/STAT3 pathway leading to improve functional recovery after SCI in rats.

Enrichment, Propagation, and Characterization of Mouse Testis-Derived Mesenchymal Stromal Cells

The therapeutic potential of multipotent stromal cells (MSCs) largely depends on the isolation and expansion methods used. In this study, we propose a laminin-based technique to select and enrich for MSCs isolated from the mouse testis. Primary cell cultures were prepared from juvenile mouse testes and the capacity to generate colony forming units together with population doubling time (PDT) during expansion were determined. The identity of MSCs was assayed using reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry for the active expression of cell surface markers, such as CD44, CD73, and CD29; absence of the CD45 hematopoietic cell marker; and in vitro differentiation of the cells into osteoblasts and adipocytes. Testis-derived MSCs (tMSCs) displayed self-renewal properties and in the early passages, exhibited high proliferation patterns with an average PDT of 44.1 hours. The lack of Vasa expression implied that the tMSCs were not of germ cell origin. The RT-PCR data, which were confirmed by immunophenotyping, revealed high expression of CD44 and the absence of CD45 expression in tMSCs. The strong Alizarin Red stain in tMSCs that were stimulated into making bone cells was indicative of the presence of calcium-producing cells (osteoblasts). Likewise, the adipogenic potential of tMSCs was demonstrated based on Oil Red O staining of lipid vacuoles in differentiated cells. Loss of fibroblast-like morphology in late passage cells along with the increase in PDT and the decrease in the mRNA levels of CD73 and CD29 suggested that the tMSCs developmental program is reformed at this stage.

Hydrogels derived from cartilage matrices promote induction of human mesenchymal stem cell chondrogenic differentiation

Limited supplies of healthy autologous or allogeneic cartilage sources have inspired a growing interest in xenogeneic cartilage matrices as biological scaffolds for cartilage tissue engineering. The objectives of this study were to determine if shark and pig cartilage extracellular matrix (ECM) hydrogels can stimulate chondrocytic differentiation of mesenchymal stem cells (MSCs) without exogenous growth factors and to determine if the soluble factors retained by these ECM hydrogels are responsible. Human MSCs cultured on hydrogels from shark skull cartilage, pig articular cartilage, and pig auricular cartilage ECM had increased expression of chondrocyte markers and decreased secretion of angiogenic factors VEGF-A and FGF2 in comparison to MSCs cultured on tissue culture polystyrene (TCPS) at one week. MSCs grown on shark ECM gels had decreased type-1 collagen mRNA as compared to all other groups. Degradation products of the cartilage ECM gels and soluble factors released by the matrices increased chondrogenic and decreased angiogenic mRNA levels, indicating that the processed ECM retains biochemically active proteins that can stimulate chondrogenic differentiation. In conclusion, this work supports the use of cartilage matrix-derived hydrogels for chondrogenic differentiation of MSCs and cartilage tissue engineering. Longer-term studies and positive controls will be needed to support these results to definitively demonstrate stimulation of chondrocyte differentiation, and particularly to verify that calcification without endochondral ossification does not occur as it does in shark cartilage.

STATEMENT OF SIGNIFICANCE

The objectives of this study were to determine if shark and pig cartilage extracellular matrix (ECM) hydrogels can stimulate chondrocytic differentiation of mesenchymal stem cells (MSCs) without exogenous growth factors and to determine if the soluble factors retained by these ECM hydrogels are responsible for this induction. Sharks are an especially interesting model for cartilage regeneration because their entire skeleton is composed of cartilage and they do not undergo endochondral ossification. Culturing human MSCs on porcine and shark cartilage ECM gels directly, with ECM gel conditioned media, or degradation products increased mRNA levels of chondrogenic factors while decreasing angiogenic factors. These studies indicate that xenogeneic cartilage ECMs have potential as biodegradable scaffolds capable of stimulating chondrogenesis while preventing angiogenesis for regenerative medicine applications and that ECM species selection can yield differential effects.

Differentiation and Molecular Properties of Mesenchymal Stem Cells Derived from Murine Induced Pluripotent Stem Cells Derived on Gelatin or Collagen

The generation of induced-pluripotential stem cells- (iPSCs-) derived mesenchymal stem cells (iMSCs) is an attractive and promising approach for preparing large, uniform batches of applicable MSCs that can serve as an alternative cell source of primary MSCs. Appropriate culture surfaces may influence their growth and differentiation potentials during iMSC derivation. The present study compared molecular properties and differentiation potential of derived mouse iPS-MSCs by deriving on gelatin or collagen-coated surfaces. The cells were derived by a one-step method and expressed CD73 and CD90, but CD105 was downregulated in iMSCs cultured only on gelatin-coated plates with increasing numbers of passages. A pairwise scatter analysis revealed similar expression of MSC-specific genes in iMSCs derived on gelatin and on collagen surfaces as well as in primary mouse bone marrow MSCs. Deriving iMSCs on gelatin and collagen dictated their osteogenic and adipose differentiation potentials, respectively. Derived iMSCs on gelatin upregulated Bmp2 and Lif prior to induction of osteogenic or adipose differentiation, while PPARγ was upregulated by deriving on collagen. Our results suggest that extracellular matrix components such as gelatin biases generated iMSC differentiation potential towards adipose or bone tissue in their derivation process via up- or downregulation of these master genes.