Stem cells in regenerative biology and medicine

Abstract

Embryonic stem cells of the mammalian blastocyst give rise to all the tissue lineages that begin to emerge at gastrulation. They are pluripotent cells and can be propagated in vitro without loss of pluripotency. Many adult tissues harbor cells that do not complete their differentiation program. These cells serve as self-renewing stem cells whose normal fate is to regenerate site-specific tissue, in response to either physiological cell turnover or damage inflicted by injury or disease. Neural, muscle, and bone marrow stem cells possess developmental potency far greater than their normal lineage-restricted fate. The understanding of the biology of stem cells is leading us into an era of regenerative medicine. The growth potential and pluripotency of embryonic stem cells and the developmental plasticity of adult stem cells, particularly those of bone marrow, make them potentially useful for replacing tissues, via transplantation or construction of bioartificial tissues, that either do not regenerate naturally or are damaged beyond their natural capability for regeneration. In addition to these two ways of replacing tissue, a third strategy of regenerative medicine is to stimulate regeneration in vivo from resident stem cells. Before these approaches become clinical reality, however, a number of basic research issues must be resolved, including the revision of our concept of a regeneration-competent cell.

Isolation, characterization and differentiation of mesenchymal stem cells from amniotic fluid, umbilical cord blood and Wharton's jelly in the horse

“…Over the past decade, stem cell research has emerged as an area of major interest due to its potential in regenerative medicine applications (Stocum 2001). The three alternative stem cells are embryonic stem cells (ESCs), adult stem cells (ASCs) and induced pluripotent stem (IPS) cells.…”

Mesenchymal Stem Cells in Bone Tissue Regeneration and Application to Bone Healing

“…These cells are identified as marrow stromal cells (supporting the cells of bone marrow), because they are relatively abundant in the bone marrow which is their suitable source. Apart from bone marrow, they are found in the endosteum of the trabecular bone, and the periosteum (Stocum 2001). A limited source of MSCs is the fat tissue, funicle blood, muscle and synovial membrane (Yoo and Johnstone 1998;Bruder et al 1997).…”

Considerações sobre a obtenção e o uso do plasma rico em plaquetas e das células mesenquimais indiferenciadas em enxertos ósseos

“…Apesar dessa capacidade, a ação osteogênica das CMIs, quando combinadas com FCs em enxertos ósseos, foi mais eficiente (BARRY & MURPHY, 2004). Por outro lado, o ambiente tissular ou molecular desfavorável pode inibir ou mesmo alterar a função osteogênica das CMIs, estimulando-as à produção de cicatriz (STOCUM, 2001).…”

“…Após o isolamento e a purificação das CMIs, estas são expandidas e repassadas a outro meio de cultura para proporcionar uma proliferação adequada para posterior utilização em transplantes (GAMRADT & LIEBERMAN, 2004). No entanto, a proliferação pode ser prejudicada pela dificuldade de reproduzir essas células in vitro (STOCUM, 2001;KREBSBACH & ROBEY, 2002;HEGEWALD et al, 2004).…”

“…A osteoindução é a diferenciação de células mesenquimais indiferenciadas (CMIs), também chamadas de células tronco, em células osteogênicas, após contato com a matriz óssea (MARTINEZ & WALKER, 1999). As CMIs são células multipotenciais presentes em vários tecidos orgânicos e, em especial, na medula óssea (STOCUM, 2001). A diferenciação e a proliferação das CMI em células osteogênicas são moduladas por alguns fatores, em especial os fatores de crescimento.…”