​The Skin Bank Unit (SBU) is one of the tissue banks under Transplant Tissue Centre in SingHealth.

Located in the Singapore General Hospital’s (SGH) Burns Centre, SBU began its operation in 1998 for the recovery, preparation, preservation and distribution of donated human skin. SBU maintains a ready supply of donor skin allografts to treat severe burn patients in Singapore during peacetime and in times of emergency.

Patients who suffer from major burns with a total body surface area (TBSA) in excess of 30% require human donated skin to cover the excised burn wounds (Figure 1). This is because there might not be sufficient donor sites to harvest their own skin for grafting.

The temporary skin allografts are life-saving as they help to prevent infection, reduce loss of critical fluids as well as relieve the patient’s pain and discomfort during the critical phase of their injury. These allogeneic tissues help to improve the patient’s morale and immunity until it is possible to graft autologous split thickness skin or cultured epithelial autograft (CEA) for definitive wound coverage.

CULTURED EPITHELIAL AUTOGRAFT (CEA)

Cultured Epithelial Autograft (CEA) consists of fully-grown skin epithelial cells (keratinocytes) in a sheet cultured typically on specialised petri dishes. The autologous human keratinocytes are isolated from a small skin biopsy of up to 4cm2 and then serially propagated in vitro with expansion ratio of up to 30 plates (total area 3,000cm2) in about 3-4 weeks.

The use of CEA mitigates the disadvantage of limited donor site for harvesting of autologous split thickness skin in large surface burns. CEA is life-saving for TBSA >50% and reduces donor site morbidity.

ALLOGRAFT-MICROGRAFT SANDWICH METHOD

Currently the SGH Burns Centre employs a two-stage procedure which involves the onlay of micrografts covered with skin allograft on debrided wounds, followed by subsequent grafting of CEAs on granulating dermis.

The micrografts of size 3mm by 3mm each are cut from autograft sheets using a specialised device. They are then manually placed piece by piece on the dermis of the skin allografts in a grid-like pattern and sandwiched between the excised wound bed and the skin allografts in the grafting procedure.

After two to three weeks, the overlaid skin allografts are carefully removed to prevent the lifting of the micrograft islands and their surrounding epithelization. This is followed by the grafting of CEA sheets, typically on granulating and non-epithelized regions (Figure 2).

Visit www.liveon.sg to find out more about legislation acts on organ and tissue donation in Singapore- Human Organ Transplant Act (HOTA) and Medical (Therapy, Education and Research) Act (MTERA)

REFERENCES

Chua, A., Khoo, Y., Thi Thu Ha, T., Woo, E., Tan, B., & Chong, S. (2018). From skin allograft coverage to allograft–micrograft sandwich method: A retrospective review of severe burn patients who received conjunctive application of cultured epithelial allografts. Elsevier Burns 44, 1032-1037.