Open Access
Adult stem cells and repair through granulation tissue
Lucio Diaz-Flores Jr1,Ricardo Gutierrez1,Juan Francisco Madrid1,Hilda Varela1,Francisco Valladares1,Lucio Diaz-Flores1
Department of Pathology, Histology and Radiology, School of Medicine, La Laguna University, Canary Islands, Spain
DOI: 10.2741/3317 Volume 14 Issue 4, pp.1433-1470
Published: 01 January 2009

Macrophage recruitment and proliferation of both small vessels (endothelium and pericytes) and fibroblast-myofibroblasts are the fundamental and provisional cellular findings in repair through granulation tissue (RTGT).Endothelium and pericytes of preexisting microvasculature may act as progenitor cells of new endothelial cells and new pericyte-fibroblast-myofibroblasts, respectively.Likewise, fibroblasts may be progenitors of themselves, and of myofibroblasts and pericytes. Moreover, all these cells may originate from circulating progenitor cells or other progenitor cells..According to this extensive cellular plasticity, this work reviews the adult stem cells (ASC) and transit- amplifying cells (TAC) related to the principal cellular components of RTGT.Moreover, we hypothesize that the perivascular region, with a heterogeneous pericyte-like cellular population, including pericytes, perivascular fibroblasts and homing cells from the bone marrow (fibrocytes and bone marrow mesenchymal cells), is the niche of progenitor cells in RTGT and the substrate of regulatory mechanisms (perivascular niche hypothesis).We also highlight RTGT as a "paracrine transitional organ" during involutive phenomena and cellular differentiation.Furthermore, we consider the combined role of both systems (ASC-TAC and RTGT) in tissue engineering and in pathological processes, such as fibrosis, organization, atherosclerosis, and tumor stroma.

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Lucio Diaz-Flores Jr, Ricardo Gutierrez, Juan Francisco Madrid, Hilda Varela, Francisco Valladares, Lucio Diaz-Flores. Adult stem cells and repair through granulation tissue. Frontiers in Bioscience-Landmark. 2009. 14(4); 1433-1470.