Tissue Inhibitor of Metalloproteinase 3 (TIMP3) mutations increase glycolytic activity and dysregulate glutamine metabolism in RPE cells.

Objectives: Mutations in Tissue Inhibitor of Metalloproteinases 3 (TIMP3) cause Sorsby's Fundus Dystrophy (SFD), a dominantly inherited, rare form of macular degeneration that results in vision loss. TIMP3 is synthesized primarily by retinal pigment epithelial (RPE) cells, which constitute the outer blood-retinal barrier. One major function of RPE is the synthesis and transport of vital nutrients, such as glucose, to the retina.

Derivation of Clinical-Grade Induced Pluripotent Stem Cell Lines from Erythroid Progenitor Cells in Xenofree Conditions.

One of the major hurdles in realizing the therapeutic potential of human-induced pluripotent stem cells (iPSC) is the generation of clinical-grade iPSC lines and their differentiated progenies for preclinical and clinical applications. Therefore, there is a need to have standardized protocols for efficient generation of clinical-grade iPSC lines from easily accessible somatic cells in feeder-free, xenofree GMP grade culture conditions without genomic integration of the reprogramming factors. Here, we provide a detailed protocol for expansion of erythroid progenitor cells from peripheral blood mononuclear cells (PBMNC) and generation of iPSC lines in feeder-free and xenofree culture conditions from these cells by using GMP grade reagents.

3D iPSC modeling of the retinal pigment epithelium-choriocapillaris complex identifies factors involved in the pathology of macular degeneration.

The retinal pigment epithelium (RPE)-choriocapillaris (CC) complex in the eye is compromised in age-related macular degeneration (AMD) and related macular dystrophies (MDs), yet in vitro models of RPE-CC complex that enable investigation of AMD/MD pathophysiology are lacking. By incorporating iPSC-derived cells into a hydrogel-based extracellular matrix, we developed a 3D RPE-CC model that recapitulates key features of both healthy and AMD/MD eyes and provides modular control over RPE and CC layers. Using this 3D RPE-CC model, we demonstrated that both RPE- and mesenchyme-secreted factors are necessary for the formation of fenestrated CC-like vasculature.

Generation of an integration-free iPSC line (CSCRi005-A) from erythroid progenitor cells of a healthy Indian male individual.

Reprogramming of somatic cells with higher genome integrity, and use of non-integrating gene delivery methods and xeno-free cell culture conditions aid in the generation of iPSCs which are more suitable for disease modelling and clinical applications. We describe here an iPSC line generated using such conditions, which expressed all the pluripotency markers, retained normal karyotype and exhibited the potential for tri-lineage differentiation, both in-vitro and in-vivo. This is the first iPSC line available from a healthy Indian individual for researchers.

Systematic evaluation of markers used for the identification of human induced pluripotent stem cells.

Low efficiency of somatic cell reprogramming and heterogeneity among human induced pluripotent stem cells (hiPSCs) demand extensive characterization of isolated clones before their use in downstream applications. By monitoring human fibroblasts undergoing reprogramming for their morphological changes and expression of fibroblast (CD13), pluripotency markers (SSEA-4 and TRA-1-60) and a retrovirally expressed red fluorescent protein (RV-RFP), we compared the efficiency of these features to identify bona fide hiPSC colonies. The co-expression kinetics of fibroblast and pluripotency markers in the cells being reprogrammed and the emerging colonies revealed the heterogeneity within SSEA-4 and TRA-1-60 cells, and the inadequacy of these commonly used pluripotency markers for the identification of bona fide hiPSC colonies.

Understanding the Molecular Basis of Heterogeneity in Induced Pluripotent Stem Cells.

Reprogramming of somatic cells to generate induced pluripotent stem cells (iPSCs) has considerable latency and generates epigenetically distinct partially and fully reprogrammed clones. To understand the molecular basis of reprogramming and to distinguish the partially reprogrammed iPSC clones (pre-iPSCs), we analyzed several of these clones for their molecular signatures. Using a combination of markers that are expressed at different stages of reprogramming, we found that the partially reprogrammed stable clones have significant morphological and molecular heterogeneity in their response to transition to the fully pluripotent state.