*3.3.2 Cleaning*

The cleaning takes place by depositing the skin in sterile jars with 10% glycerol, followed by a manual agitation for 5 minutes. The process is repeated five times in different jars. During this procedure, jars change from a tainted red color to transparent. Concomitant, new samples are taken for culture. Finally, the last jar with skin sheets in a cryopreserving solution (glycerol 10%) is carefully transferred to refrigeration (between 2 and 8°) for at least 1 hour.

*Banks of Cryopreserved Skin from Live Donors and Total Skin Allografts in the Surgery of… DOI: http://dx.doi.org/10.5772/intechopen.104451*

#### *3.3.3 Final packing and labeling*

This phase includes measuring, packing, and labeling each piece of the skin set. It is done once the tissue has been immersed in the cryopreserved solution (glycerol 10%) for at least 1 hour.

Samples for culture (current, anaerobic, and fungal) are taken at the beginning and end of the packing. The packing used to pack the skin is completely transparent, allowing the tissue visualization with its features and conditions. The obtained tissue is then labeled according to internal codes, with the information needed for their traceability. It is important to emphasize that in contrast to organ transplant, where a donor usually benefits one receptor, tissue transplants from one donor may benefit many receptors.

#### **3.4 Storage**

The processed skin is kept in quarantine in an ultra freezer at 80°C until the skin cultures, and donor serology results are obtained. Following the entrance of the samples, the clinical laboratory usually informs the results of the aerobic cultures in 72 hours and the fungal cultures in 15 to 18 days. If any culture develops any microorganism (positive result), the table of microorganisms allowed in the skin for radiation (**Table 3**) is consulted to determine if the skin set will complete the final phase of radiation or will be discarded.

#### **3.5 Radiation**

The objective is the sterilization of the CTSCA and bacterial contamination risk reduction, using gamma radiation (25 to 30 kGy). Dry ice must be used to keep the cold chain during the skin transportation from the skin bank to the radiation center.

Twenty-five kilograms of gamma radiation to an ultra-frozen skin with low glycerol concentration sterilize the tissue with no histological, cytotoxic, or physical alteration, in contrast to normal cryopreserved skin [47, 48]. Only tissues with a negative serology from the patient and negative cultures or accepted microorganisms for radiation will complete the final radiation process.

#### **3.6 Distribution**

Facing the CTSCA requirements, the skin sets must be transferred in dry ice, in a pellet-like presentation, keeping the temperature between 76 and 80°C from skin banks to the different hospitals for their clinical use.


**Table 3.**

*List of microorganisms allowed in skin for radiation.*

#### **3.7 Clinical use**

In the preoperative phase, the size of the defect to be covered must be calculated to request the appropriate amount and size of skin sheets. All the information that guarantees tissue traceability and biovigilance from the donor and the final receptors must be consigned.

It is essential to emphasize the elasticity of the CTSCA, which may also expand doing small incisions on its epidermal layer, so the cover surface of the CTSCA is more extensive than its size.

In the preoperative, the size of the defect to be covered must be calculated to request the appropriate amount and size of skin sheets. It is essential to emphasize the elasticity of the CTSCA, which may also expand doing small incisions on its epidermal layer, so the cover surface of the CTSCA is more extensive than its size.

Prior to clinical use, the CTSCAs are washed three times with warm physiological saline (without exceeding 40°C) to remove the cryoprotectants (glycerol 10%).

The receptor bedding is prepared with scarectomy of the necrotic, devitalized, and disorganized granulation tissue; subsequently, the CTSCA is fixed in our case with stitches and/or medical clasps associated with negative pressure therapy [49].

All the skin processing, from donation to clinical use, is resumed in the flow diagram of **Figure 4**.
