Mesenchymal Stem Cells in Clinical Applications

Interplay of matrix stiffness and stress relaxation in directing osteogenic differentiation of mesenchymal stem cells

The aim of this study is to investigate the impact of the stiffness and stress relaxation of poly(acrylamide-co-acrylic acid) hydrogels on the osteogenic differentiation of human mesenchymal stem cells (hMSCs). Varying the amount of the crosslinker and the ratio between the monomers enabled the obtainment of hydrogels with controlled mechanical properties, as characterized using unconfined compression and atomic force microscopy (AFM). Subsequently, the surface of the hydrogels was functionalized with a mimetic peptide of the BMP-2 protein, in order to favor the osteogenic differentiation of hMSCs. Finally, hMSCs were cultured on the hydrogels with different stiffness and stress relaxation: 15 kPa - 15%, 60 kPa - 15%, 140 kPa - 15%, 100 kPa - 30%, and 140 kPa - 70%. The cells on hydrogels with stiffnesses from 60 kPa to 140 kPa presented a star-like shape, typical of osteocytes, which has only been reported by our group for two-dimensional substrates. Then, the extent of hMSC differentiation was evaluated by using immunofluorescence and by quantifying the expression of both osteoblast markers (Runx-2 and osteopontin) and osteocyte markers (E11, DMP1, and sclerostin). It was found that a stiffness of 60 kPa led to a higher expression of osteocyte markers as compared to stiffnesses of 15 and 140 kPa. Finally, the strongest expression of osteoblast and osteocyte differentiation markers was observed for the hydrogel with a high relaxation of 70% and a stiffness of 140 kPa.

Evaluating Poly(Acrylamide-co-Acrylic Acid) Hydrogels Stress Relaxation to Direct the Osteogenic Differentiation of Mesenchymal Stem Cells

The aim of this study is to investigate polyacrylamide-based hydrogels stress relaxation and the subsequent impact on the osteogenic differentiation of human mesenchymal stem cells (hMSCs). Different hydrogels are synthesized by varying the amount of cross-linker and the ratio between the monomers (acrylamide and acrylic acid), and characterized by compression tests. It has been found that hydrogels containing 18% of acrylic acid exhibit an average relaxation of 70%, while pure polyacrylamide gels show an average relaxation of 15%. Subsequently, hMSCs are cultured on two different hydrogels functionalized with a mimetic peptide of the bone morphogenetic protein-2 to enable cell adhesion and favor their osteogenic differentiation. Phalloidin staining shows that for a constant stiffness of 55 kPa, a hydrogel with a low relaxation (15%) leads to star-shaped cells, which is typical of osteocytes, while a hydrogel with a high relaxation (70%) presents cells with a polygonal shape characteristic of osteoblasts. Immunofluorescence labeling of E11, strongly expressed in early osteocytes, also shows a dramatically higher expression for cells cultured on the hydrogel with low relaxation (15%). These results clearly demonstrate that, by fine-tuning hydrogels stress relaxation, hMSCs differentiation can be directed toward osteoblasts, and even osteocytes, which is particularly rare in vitro.

Mesenchymal stem cells for restoring endometrial function: An infertility perspective

BACKGROUND

Mesenchymal stem cells (MSCs) can be derived from several tissues such as bone marrow, placenta, adipose tissue, or endometrial tissue. MSCs gain a lot of attention for cell-based therapy due to their characteristics including differentiation ability and immunomodulatory effect. Preclinical and clinical studies demonstrated that MSCs can be applied to treat female infertility by improving of the functions of ovary and uterus. This mini- review focuses on the current study of treatment of endometrial infertility by using MSCs.

METHODS

The present study performed a literature review focusing on the effect of MSCs for treatment of women infertility caused by endometrial dysfunction.

RESULTS

Bone marrow-, umbilical cord-, adipose-, amniotic-, and menstruation-derived MSCs enhance endometrial cell proliferation, injury repairs as well as reducing scar formation. The beneficial mechanism probably via immunomodulatory, cell differentiation, stimulates endometrial cell proliferation and down-regulation of fibrosis genes. The major advantage of using MSCs is to improve endometrial functions resulting in increased implantation and pregnancy.

CONCLUSIONS

MSCs exhibit a potential for endometrial infertility treatment. Adipose- and menstruation-derived stem cells show advantages over other sources because the cells can be derived easily and do not causes graft rejection after autologous transplantation.

Pericytes and their potential in regenerative medicine across species

The discovery that pericytes are in vivo counterparts of Mesenchymal Stem/Stromal Cells (MSCs) has placed these perivascular cells in the research spotlight, bringing up hope for a well-characterized cell source for clinical applications, alternative to poorly defined, heterogeneous MSCs preparations currently in use. Native pericytes express typical MSC markers and, after isolation by fluorescence-activated cell sorting, display an MSC phenotype in culture. These features have been demonstrated in different species, including humans and horses, the main targets of regenerative treatments. Significant clinical potential of pericytes has been shown by transplantation of human cells into rodent models of tissue injury, and it is hoped that future studies will demonstrate clinical potential in veterinary species. Here, we provide an overview of the current knowledge on pericytes across different species including humans, companion and large animal models, in relation to their identification in different body tissues, methodology for prospective isolation, characterization, and potential for tissue regeneration. © 2017 International Society for Advancement of Cytometry.