No abstract

In this work, different fibroblast-like (mesenchymal) cell populations that might be involved in wound healing were characterized and their involvement in scar formation was studied by determining collagen synthesis and processing. Depending on the physical and mechanical properties of the tissues, specific collagen cross-linking routes are followed. In skin the cross-linking of the pyridinium type is normally very low; however, in different forms of fibrosis increased levels of this type of cross-linking have been found. The enzyme lysyl hydroxylase-2b (LH-2b) plays a crucial role in this type of cross-linking. The gene expression levels of LH-2b, alpha-smooth muscle actin, and collagen types I and III were determined in dermis, subcutaneous fat, and (hypertrophic) scar tissue as well as in isolated cultured mesenchymal cells derived from these tissues, by real-time RT-polymerase chain reaction. Cultured mesenchymal cells from fat and scar tissue as well as the tissues itself showed significantly higher expression of LH-2b, alpha-SMA, and collagen type I than dermal mesenchymal cells. LH-2b-dependent pyridinium cross-linking was significantly enhanced in fat and scar tissue compared with dermis. FACS analysis was performed to characterize the fibroblast-like cells from the dermis, fat, and scar tissue. All cell populations express the distinct pattern of CD markers also expressed by mesenchymal stromal cells. Furthermore, parts of these cell populations were able to differentiate into adipocytes, chondrocytes, and osteoblasts. We conclude, therefore, that mesenchymal (stem) cells from the subcutaneous fat might be responsible for the accumulation of collagen in these scars.

The quality of skin wound healing can be improved by the application of scaffolds as skin replacement materials. Although the clinical requirements for the function of such materials are defined, the translation of these requirements into physical and mechanobiological properties of scaffolds is difficult. Natural as well as constructed biological materials and synthetic substitutes are discussed. Furthermore, new techniques such as electrospinning and solid freeform fabrication as well as new types of materials such as self-assembling peptides are reviewed with regard to their potential role in the production of skin substitute materials.

This study compares mesenchymal cells isolated from excised burn wound eschar with adipose-derived stem cells (ASCs) and dermal fibroblasts in their ability to conform to the requirements for multipotent mesenchymal stem cells (MSCs). A population of multipotent stem cells in burn eschar could be an interesting resource for tissue engineering approaches to heal burn wounds. Cells from burn eschar, dermis, and adipose tissue were assessed for relevant CD marker profiles using flow cytometry and for their trilineage differentiation ability in adipogenic, osteogenic, and chondrogenic conditions. Although the different cell types did not differ significantly in their CD marker expression, the eschar-derived cells and ASCs readily differentiated into adipocytes, osteoblasts, and chondrocytes, while dermal fibroblasts only exhibited some chondrogenic potential. We conclude that the eschar-derived mesenchymal cells represent a population of multipotent stem cells. The origin of the cells from burn eschar remains unclear, but it is likely they represent a population of adult stem cells mobilized from other parts of the body in response to the burn injury. Their resemblance to ASCs could also be cause for speculation that in deep burns the subcutaneous adipose tissue might be an important stem cell source for the healing wound.