Recent Articles of Interest

Fibroblast growth factor (FGF) signaling is involved in a wide range of crucial organical activities with differential actions in various cell types. The activity of FGF is modulated by glycosaminoglycans, located both in the extracellular matrix and on the cell surface.

These molecules are crucial in injury healing. Such a dynamic process is interactive and depends on an adequate regulation of fibroblasts.

Without control of these processes, excessive scar tissue develops. As a result of inefficient healing, keloids and hypertrophic scars often become a problem. These are both difficult health conditions that affect people's quality of life, due to high treatment costs and frequent poor results.

A Fibroblast is a kind of cell that stimulates the proliferation of keratinocytes and the synthesis of glycosaminoglycans, and glycoproteins located in the extracellular matrix. The proliferation of fibroblasts enhances the epidermal morphology.

Keratinocytes appear in the basal layer from the mitosis of keratinocyte stem cells. They are pushed up through the cells of the epidermis, experiencing gradual specialization until they join the stratum corneum where they create a layer of enucleated, flattened, strongly keratinized cells named squamous cells. This layer creates an effective barrier to the entry of foreign matter and infectious agents in the body and minimizes moisture loss.

Keratinized Cells

Typically occurring during the process of scar removal keratinocytes are shed and restored constantly from the stratum corneum. The time of transit from the basal layer to the shedding stage is approximately one month, although this can be sped up in conditions of keratinocyte hyperproliferation, such as psoriasis.

The simplest definition of a stem cell in an adult organism is any cell with an elevated capacity for self-renewal that remains throughout adult life. In addition, stem cells are usually considered to have the potential to produce differentiated progeny.

According to these criteria, the epidermis has long been recognized as having a resident stem cell stock. The tissue is made of a stratified squamous epithelium (interfollicular epidermis; IFE) with associated capillary follicles and glandular structures (the sebaceous glands and sweat glands).

The IFE undergoes constant turnover and there is always a need to replace the devitalized, ultimately specialized cells of the outermost cornified layers through the proliferation of cells in the basal layer.

It is now well accepted that stem cells within the epidermis are multipotent and capable of producing daughter cells that differentiate along multiple lineages. Stem cells inside the hair follicle bulge can create progeny that differentiate not only in all the capillary follicle lineages, but also in sebocytes and the interfollicular epidermis.

Following exposure to appropriate mesenchymal signals, cells of the interfollicular epidermis are able of originating hair or sebaceous lineages. There is, however, evidence for the presence of distinct stem cell populations within the IFE and sebaceous gland. These observations can be reconciled by afirming that there are separate stem cell populations within the hair, sebaceous gland and IFE.

Each of these can create daughters that differentiate along any of the skin lineages. In steady conditions, however, the stem cells usually give rise to a more restricted repertoire in reaction to signals from the local microenvironment.