Chapter 5, Problem 1DQ

Summary Introduction

To review:

Whether such a term “stem cellness” exist, and whether it is intrinsic property of the cell or property acquired through interactions with the stem cell niche. Whether niche is making the stem cell and how these conditions exist in a particular organ.

Introduction:

Stem cell is an undifferentiated and unspecialized tissue that gives rise to a specific specialized cell like blood cell. A stem-cell niche is an area of a tissue providing specific microenvironment, where stem cells are present in an undifferentiated and self-renewable state. Adult stem-cell niche is controlled by universal mechanism that control stem-cell development.

Explanation of Solution

“Stem cellness” is not a property identified in any cell. Stem cell has ability to differentiate in all the cell types of lineage known as totipotent cells. Cells of the stem-cell niche interact with the stem cells to maintain them or promote their differentiation. Many adult tissues and organs contain stem cells that undergo renewal. Adult stem cell is controlled by its own adult stem cell niche, which regulates stem cell survival, self-renewal, and differentiation of progeny that leaves niche.

Stem cell niches of adult humans

Stem cell type	Niche location	Cellular components of niche
Low turnover Brain (neurons and glia) Skeletal muscle	Ventricular-subventricular zone, subgranular zone Between basal lamina and muscle fibers	Ependymal cells, blood vessel epithelium Muscle fiber cells
High turnover Mesenchymal stem cells (MSCs) Intestine Hematopoietic stem cells (HSCs) Epidermis (skin) Hair follicle Sperm	Bone marrow, adipose tissue, heart, placenta, umbilical cord Base of small intestinal crypts Bone marrow Basal layer of epidermis Bulge Testes	Probably blood vessel epithelium Paneth cells, MSCs Macrophages, Treg cells, osteoblasts, pericytes, glia, neurons, MSCs Dermal fibroblasts Dermal papillae, adipocyte precursors, subcutaneous fat, keratin Sertoli cells

The low turnover indicates generate stem cells for repair, slow growth, and learning. The high turnover indicates new cell production for bodily maintenance.

Conclusion

Therefore, it is concluded that there is no such thing as “Stem cellness.” Stem cell is a property acquired through interactions with the stem cell niche.