Pluripotent Stem Cells and Their Dynamic Niche

Abstract

Cell-seeded implants are a regenerative medicine strategy that aims to replace injured tissue and restore tissue function. Pluripotent stem cells are promising cell candidates for the development of regenerative medicine therapies as they have the ability to selfrenew and commit towards numerous cell types. In vivo, stem cells reside in a dynamic niche, a stem cell-specific microenvironment that possesses chemical, biological and mechanical cues, which drive the stem cell fate and renewal. The connection between stem cells and their niche is a two-way relationship consisting of both cell-cell interaction and cell-extracellular matrix (ECM) interactions. An alternative regenerative medicine approach is the manipulation of the stem cell microenvironment. Hence, novel strategies have been developed including 3D biomaterials and bioreactor technologies providing topographical, chemical and mechanical cues to recreate the stem cell niche. Understanding the mechanisms controlling stem cell fate and the dynamic nature of the stem cell niche will enable researchers to replicate this stem cell-specific microenvironment, and therefore, harness and control the valuable attributes which stem cells possess. This chapter elucidates the importance of pluripotent stem cells and their dynamic niche in regenerative medicine. It further presents novel strategies to replicate chemical, topographical and mechanical stimuli which are essential for the regulation of stem cell fate and hence tissue regeneration.

Hydrostatic pressure promotes chondrogenic differentiation and microvesicle release from human embryonic and bone marrow stem cells

“…[ 1 ] Tissue engineering strategies using sources of stem cells, either allogeneic or autologous, present promising approaches for cartilage repair in OA patients. To date, researchers have explored various cell sources for cartilage tissue engineering application, including embryonic stem cells [ 2,3 ] and adult stem cells derived from tissues such as bone marrow, [ 4 ] synovium, [ 5 ] and infrapatellar fat pad, [ 6,7 ] among which bone marrow stem cells (BMSCs) are the most intensively investigated. Studies have demonstrated successful chondrogenic induction of BMSCs over various culture protocols such as pellet, [ 8 ] natural hydrogel, [ 4,9 ] and synthetic polymers.…”

Extracellular Matrix Hydrogels Originated from Different Organs Mediate Tissue-Specific Properties and Function

“…To this end, we evaluated the adherence of hiPSCs to hydrogels supplemented with the native protein crosslinkers, genipin and EGCG, [ 24 , 25 , 45 ] and chose the most appropriate combination for the differentiation studies. When culturing hiPSCs on the pECM hydrogels, different adherence and proliferation levels were obtained, as the hiPSCs are influenced by their immediate surrounding containing specific molecules for their growth and differentiation [ 55 ]. However, all the hydrogels supported hiPSCs culture for at least 28 days.…”

Recent advances on identification of spermatogonial stem cells and their niche

“…Niche-derived extrinsic stimuli and intrinsically expressed factors regulate stem cell self-renewal and differentiation that provide the foundation for testis homeostasis (Reinwald et al, 2016). Unlike the welldefined and distally localized germline stem cell niche in the gonads of other model organisms, such as Drosophila and C. elegans, the mammalian testis contains many potential germline stem cell niches (in the range of several thousand to 40,000 per testis) (Tegelenbosch and de Rooij, 1993;Shinohara et al, 2001) that are not well characterized, but are believed to be randomly located along the tubules.…”