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INTRODUCTION

SUMMARY POINTS

What’s Important?

  1. Fibroblasts produce collagen, elastin precursors, and ECM constituents such as hyaluronic acid and heparan sulfate.

  2. Young skin is characterized by elongated fibroblasts that are more productive (synthesize more collagen and ECM components) than those in older skin.

  3. Old fibroblasts become compact and have less connection to the ECM.

What’s New?

  1. The tissue skeleton connects the fibroblast genomic DNA to the ECM.

  2. The fibroblast connects to the ECM and exerts “mechanoforces” that affect gene expression.

  3. Geometrical changes in the nucleus of the fibroblast influence gene transcription.

  4. The matrisome, or microenvironment of the ECM, affects the gene expression of fibroblasts.

  5. Papillary fibroblasts and reticular fibroblasts exhibit a 29% difference in gene expression1 and different cell markers.

What’s Coming?

  1. Linkers of the nucleoskeleton and cytoskeleton (LINCS) are connected to genomic DNA. Research is ongoing to understand how LINCS affects DNA expression and to which signals they respond.

  2. Ongoing research is assessing the tissue skeleton and modulations that occur with aging.

  3. More is to be learned about epigenetics and the effects on fibroblast function.

  4. More will be learned about cannabinoid receptors and fibroblasts.

The dermis lies between the epidermis and the subcutaneous fat. It is responsible for the thickness, strength, elasticity, and volume of the skin, and as a result plays a key role in the cosmetic appearance of the skin. The thickness of the dermis varies over different parts of the body and the size doubles between the ages of 3 and 7 years and again at puberty. The dermis is laden with nerves, blood vessels, melanocytes, and sweat glands surrounded by extracellular matrix, collagen, elastin, and hyaluronic acid (HA).

The dermal layer contributes most to the aged appearance of the skin. With aging, the dermal layer decreases in thickness and function. Fibroblasts become sluggish, less responsive to cell signals, and divide less frequently with age. These changes result in thinner skin with fine lines and wrinkles. Loss of elastin in this layer leads to skin sagging, while loss of collagen yields fragility, and loss of HA engenders a decrease in moisture-holding capacity and volume. The dermis is the layer where dermal fillers are injected to increase volume and improve the skin’s appearance. Although the epidermis reflects light, gives skin its texture, and regulates moisturization, changes in the epidermis affect the skin’s appearance temporarily because of this layer’s rapid cell turnover. Dermal changes are more durable and significant, but these less superficial changes take longer to see. Dysfunction of the dermis causes long-term issues like keloids, stretch marks, and acne scars. Protection of the dermis is critical because many problems located in this layer cannot be completely corrected.

ANATOMY OF THE DERMIS

The Dermal-Epidermal Junction

The dermal-epidermal junction (DEJ) is made up of the lower basement membrane of the basal keratinocytes and is an extremely important area of the skin ...

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