Mechanisms of Cell Regeneration — From Differentiation to Maintenance of Cell Phenotype

Abstract

In adult organisms the regenerative capacity of certain organs or tissues can be limited, resulting in an important clinical challenge for physicians and scientists [1-3]. Regeneration involves the capacity for renewal or recomposition of tissues, organs or even organisms, after considerable physical injury or damage, resulting from pathologies, tumors, congenital diseases or traumas, for example. As a consequence of tissue regeneration, both the composition and the tissue properties are restored, and the newly formed tissue is highly similar to the original tissue. The regenerative capacity is directly related to the presence of stem cells or progenitor cells, which are capable of proliferation and differentiation [4,5]. Tissues that maintain a high proliferative capacity, such as the hematopoietic system, have regenerative capacity even in adult organisms [6]. Cell proliferation occurs in repair processes in general, accompanied by intense production of extracellular matrix, with large amounts of collagen, resulting in the formation of fibrous tissue to occupy the injured area. Although there is lesion filling, both the composition and the tissue properties are different from the original tissue, and the tissue organization pattern is not restored, leading to an altered performance of its functions [2]. Skin healing processes with the presence of scars are examples of tissue repair [3]. Besides the natural processes of regeneration and repair, it is possible, through medical intervention, to fill lesions with natural or synthetic materials, aiming at the recovery of the

Evaluation of Soft Tissue Regenerative Processes After Subcutaneous Implantation of Silver/ Poly(Vinyl Alcohol) and Novel Silver/Poly(Vinyl Alcohol)/Graphene Hydrogels in an Animal Model

“…Laminins and related ECM components, have essential roles in tissue homeostasis and during wound healing, they take part in the skin renewal process [39,40] Our research noted that after implantation of Ag/PVA and Ag/PVA/Gr, the distribution of laminin in the tissue was high in various skin cells, including epithelial cells, muscle and endothelial cells, as well as in the ECM of the dermis, and connective tissue capsules. These fi ndings are consistent with literature data [41][42][43], although the results obtained in the implant zone cannot be compared with data of other authors, since there have not been in vivo studies with newly synthesized Ag/PVA/Gr so far. The increased expression of laminin in the case of Ag/PVA/Gr in all observed time periods, in relation to the intact skin control, is a consequence of its involvement in cell migration, adhesion and differentiation during active tissue remodeling induced by implanted material itself.…”

“…It is tightly regulated by degradation and synthesis, leading to normal skin regeneration [44]. Tissue regeneration begins by restoring the tissue damage, fi rstly by removing dead cells, then by proliferation of progenitor cells and lastly, functional restoration of the tissue [42]. Apoptosis is involved in the processes of wound healing and tissue regeneration, with the basic role of removing infl ammatory cells and granulation tissue [47,48].…”

Biomaterials for Cell Regeneration

“…Figure 2 shows role of biomaterials in tissue regeneration. The event are; (i) Bioelectric signalling, (ii) Thrombin activation, (iii) Influence of the immune response and (iv) Wound epithelium formation [6]. Bioelectric signalling includes electric flows in injury that flows after the removal of appendages and mirrors the geometry of the altered tissue and subsequently, the electrical opposition.…”

Factors and molecules that could impact cell differentiation in the embryo generated by nuclear transfer

“…The differentiated state of cells is very stable, and it is unusual to change fate of cells that have embarked on one pathway of differentiation. 6 In mammals, the most obvious defects of SCNT-derived embryos are related to the placenta. Commonly observed abnormalities include shorter life span, enlarged placenta, obesity, respiratory problems, and large offspring syndrome.…”