Stem Cell

Adult stem cells not only maintain tissue homeostasis but are also critical for tissue regeneration during injury. Skeletal stem cells are multipotent stem cells that can even generate bones and cartilage upon transplantation to an ectopic site. This tissue generation process requires essential stem cell characteristics including self-renewal, engraftment, proliferation, and differentiation in the microenvironment. Our research team has successfully characterized and isolated skeletal stem cells (SSCs) from the cranial suture called suture stem cells (SuSCs), which are responsible for craniofacial bone development, homeostasis, and injury-induced repair. To assess their stemness features, we have demonstrated the use of kidney capsule transplantation for an in vivo clonal expansion study. The results show bone formation at a single-cell level, thus permitting a faithful assessment of stem cell numbers at the ectopic site. The sensitivity in assessing stem cell presence permits using kidney capsule transplantation to determine stem cell frequency by limiting dilution assay. Here, we described detailed protocols for kidney capsule transplantation and limiting dilution assay. These methods are extremely valuable both for the evaluation of skeletogenic ability and the determination of stem cell frequency.

The goal of this protocol is to establish a procedure for cultivating stem cells on a fibrin carrier to allow for eventual transplantation to the eye. The ability to transfer stem cells to a patient is critical for treatment for a variety of disorders and wound repair. We took hair follicle stem cells from the vibrissae of transgenic mice expressing a dual reporter gene under the control of the Tet-on system and the keratin 12 promoter (Meyer-Blazejewska et al., 2011). A clonal growth assay was performed to enrich for stem cells. Once holoclones formed they were transferred onto a fibrin carrier and cultivated to obtain a confluent epithelial cell layer. Limbal stem cell deficient (LSCD) mice were used as the transplant recipient in order to test for successful grafting and eventual differentiation into a corneal epithelial phenotype.

Stem and progenitor cells isolated from human limbal tissue can be cultured in vitro as spheres. These spheres have potential for use as transplantable elements for the repopulation of corneal tissue (Mathan et al., 2016). Herein we describe the detailed protocol for the implantation of human corneal spheres into cadaveric human corneal tissue. This protocol describes the procedure for sphere formation and culture, preparation of tissue for sphere implantation, corneal limbus microsurgery and sphere implantation.

Liver fibrosis results from the excessive collagen deposition (collagen scar) by activated hepatic stellate cells (HpSCs), leading to the inhibition of normal liver regeneration and function. Fibrogenesis is a complex mechanism involving both the synthesis and degradation of matrix proteins by different cell types, mainly macrophages in the liver. Carbon tetrachloride-induced fibrosis (CCl₄) and cirrhosis is one of the oldest, simplest and probably the most widely used toxin-based experimental model for the induction of fibrosis. Here we have explained experimental animal model of liver fibrosis using CCl₄, injecting twice a week for a period of 8 weeks. In these fibrotic mice, bone marrow (BM) derived CD45⁺ cells were transplanted via intrasplenic route after 8 weeks of CCl₄ injection, and half of the CCl₄ dose was continued till the end of the experiment to know the effect of transplanted cells on liver fibrosis and regeneration. So far, crude bone marrow (BM) cells or mesenchymal stem cells (MSCs) have been used for the treatment of liver fibrosis. Low survival rate, less fibrolytic and profibrogenic properties of MSCs remain the major concerns for inadequate recovery of liver from fibrosis. This led us to investigate BM cells devoid of mesenchymal lineage that is CD45⁺ cells for the antifibrotic effect as this population consisting of mononuclear cells which are the precursor of macrophages and may involve in the scar degradation process. Cells transplantation can be followed in different ways like intrasplenic infusion, tail vein injection and ectopic cell transplantation in experimental animal models. The survival of the cells after ectopic transplantation is less when compared to tail vein and intrasplenic infusion. Intrasplenic route of transplantation is effective in engraftment and long term survival of the donor cells especially in case of liver disease models. This protocol describes fibrosis mouse model development, intrasplenic route of cell transplantation and tracking of the donor cells after transplantation.