Before recent technological developments, the standard care for wounds resulted in substantial scarring and discomfort. However, a new approach that is preventative of permanent scarring is now available. In a recent issue of Advances in Skin & Wound Care, Dr. Sandra Osborne and colleagues set out to demonstrate how epidermal micrografts, a less invasive form of wound repair, help in the formation of the dermal-epidermal junction, as well as growth factor secretion.  In short, epidermal micrografts are small insertions into the body in which epidermal tissue is immersed into a swollen surface.

This reformed process of micrografting includes harvesting, which is the process of removing some of the epidermal layer from a donor and implanting that tissue on a specific site of the epidermal layer of the patient. This process is similar to skin grafting, but it does not result in significant donor site damage and scarring.  In general, wound treatments range from topical creams and dressings to autologous split-thickness skin grafts (STSG), which is a skin graft that includes the dermis layer of the skin. The preparation and procedure of STSG is intensive and can result in donor-site trauma, scarring, and graft rejection.  On the other hand, epidermal grafts are superficial (right below the surface of the skin) compared to STSG, resulting in fewer traumas.  Epidermal harvesting has been limited in the past due to the extensive time involved and variable methodologies that have yielded inconsistent results. A new option now commercially available that overcomes these challenges is an automated epidermal-harvesting tool called CelluTome, engineered by Kinetic Concepts Inc. This tool applies heat and suction simultaneously to produce epidermal micrografts in less than 40 minutes, without the use of anesthesia and with minimal patient discomfort.

A new option now commercially available that overcomes these challenges is an automated epidermal-harvesting tool called CelluTome, engineered by Kinetic Concepts Inc.

Dr. Osborne and colleagues performed a prospective study on the CelluTome tool used for epidermal-harvesting. The small study included 15 healthy volunteers. This study group included eight men and seven women.  All the participants were white and within the age range of 42-70 years, with an average age of 51.9 years. Using the epidermal-harvesting tool, CelluTome, micrografts were created on the inner thighs of the 15 participants.  The CelluTome tool applied heat at a temperature of 37° C– 41° C and simultaneously applied suction vacuum pressure. Using this tool, 128 epidermal micrografts were collected.

For the purpose of histological (tissue) analysis, micrograft samples from 12 subjects were used and noted as evaluation population 1(EV1).  The micrograft cross-section was stained with an antibody called Ki67, and a compound called hematoxylin, which is a natural dye that stains nuclei. These micrografts were further tested and cultured in vitro to look for keratinocytes, cells that produce a key material called keratin which helps prevent the epithelial cells from being damaged.  Furthermore, the micrografts were tested for outgrowth in melanocytes, which are cells that produce melanin, a compound responsible for pigmentation of skin. Ten micrografts were placed onto plates primarily containing collagen, which are proteins that form fibers that are a primary component of connective tissue.  In order to determine growth factor secretion, samples from three subjects were used and noted as “evaluation population 2” (EV2).  Similar to the histological analysis, a process of secreted growth factor analysis was performed on these micrographs under conditioned media for seven days.

Successful grafting depends on precise separation of the dermal-epidermal layers of the skin with an intact basal layer, allowing for growth of basal layer cells to occur. This process allows keratinocytes, which form the primary cells of the epidermis, to continue to grow and secrete cytokines as well as other growth factors when stimulated.  

The primary limitation to this experiment was the small sample size used for the study, which brings into question whether these results can actually be inferentially applied to a larger population. Additionally, the sample size was not racially diverse, as it only included white participants. Whether the amount of melanin pigment affects this process is an important question.

The combined effect of applying heat and suction caused partial delamination of the basement membrane of the skin. Key growth factors are released by basal cells, including vascular endothelial growth factor, hepatocyte growth factor, granulocyte colony stimulating growth factor, platelet derived growth factor, and transforming growth factor. Results revealed that epidermal micrografts formed at the dermal-epidermal junction using this method, as desired. Migratory keratinocytes (making the outer layer of the skin) and melanocytes (allowing skin pigmentation) were noted to proliferate at the junction, as desired. This discovery has made researchers optimistic that the  formation of skin, and re-pigmentation of the wound is high using the CelluTome tool.

Results revealed that epidermal micrografts formed at the dermal-epidermal junction using this method, as desired.

The option for epidermal harvesting without causing major donor site damage and scarring is significant to the medical community because it provides a more efficient and safer option for wound repair. This procedure helps eliminate the risk of scarring by using epidermal micrografts, as previously described. More over, there is minimal pain associated with this procedure, compared to the typically traumatic and painful process of STSG. The CelluTome tool provides the patient the opportunity to remain awake throughout the process, and the procedure only takes 40 minutes. In an age where instant gratification is the norm, this technology should be especially appealing because it provides instant results.


REFERENCES

Osborne, S., Schmidt, M., Derrick, K., & Harper, J. (2015). Epidermal Micrografts Produced via an Automated and Minimally Invasive Tool Form at the Dermal/Epidermal Junction and Contain Proliferative Cells That Secrete Wound Healing Growth Factors. Advances in Skin & Wound Care, 397-405.

 

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