Wound Repair Using Discarded Skin Tissue From the Rolled Edge of Pressure Injury: A Feasibility Study of Five Cases

Chronic wounds deserve more attention because of their increased incidence and associated mortality. In China, PI is the second most common cause of chronic wounds,¹ which requires high-quality health care and imposes a substantial financial burden on affected patients and their families as well as society. Effective treatment is required to resolve this problem. Currently, several efficient strategies exist to manage chronic wounds, including skin grafting and flap transplantation. However, these options are limited by factors such as the need for anesthesia, operating room time, donor site morbidity, and severe patient comorbidities.^2-4

In chronic wounds, maceration, dehydration, undermining, and rolled edges are common at the wound edge.⁵ During dressing change or debridement, the skin tissue of the rolled edge is typically excised and discarded as medical waste. Before the current study, the authors obtained a piece of rolled edge tissue of a patient’s wound in the outpatient setting. This section is stained with hematoxylin-eosin, and abundant keratinocytes are observed under light microscopy. In 2011, Sun et al⁶ reported on the dedifferentiation ability of keratinocytes. The authors of the current case series hypothesized that the discarded skin tissue from the rolled edge of a PI, which is rich in keratinocytes, might be used as a new skin donor site in the repair of chronic wounds.

The aim of this study was to harvest skin particles from the rolled edge of PIs to investigate the viability and proliferative ability of keratinocytes from these particles, and to evaluate the feasibility of using these skin particles in the treatment of chronic wounds.

Patients

Dependent persons aged 65 years and older and with a single grade 3 or 4 PI of greater than 2 weeks’ duration were enrolled in this study. According to the NPIAP’s revised definition of pressure injury,⁷ a grade 3 PI is described as full-thickness skin loss with damage to subcutaneous tissue, but it is not deeper than the underlying fascia. A grade 4 PI includes extensive destruction of underlying tissues, including muscle and possibly bone and supporting structures.⁷ All study participants were provided written informed consent forms, which were signed by a member of their immediate family. Exclusion criteria included persons with 2 or more PIs, patients in critical condition, a serum albumin level less than 25 g/L, and the presence of a tumor or systemic disease. This study was approved by the ethical committee of the authors’ hospital, and investigations were conducted in accordance with the Declaration of Helsinki.

Wound bed preparation

Grafting was performed when wound beds were covered with at least 50% fresh granulation tissue and no necrotic tissue remained. For wound bed preparation, PIs were treated conventionally, including removal of necrotic tissue and exudation fluids. The NPWT devices were also used during the wound preparation procedure to accelerate growth of granulation tissue. Antimicrobial agents were administered as necessary, according to the bacteriological analysis. The wound size was measured manually with a printed grid net (measuring 1 cm × 1 cm) and was recorded both before grafting and 1 month after grafting.

Split skin preparation and
transplantation

Split skin tissue approximately 0.05 cm to 0.1 cm thick was harvested from the rolled edge of the ulcer with a scalpel and cut into small particles measuring approximately 0.3 cm × 0.3 cm. The skin particles were transferred to the surface of the prepared wound bed with forceps, leaving more than 0.5 cm of space between each particle, and then covered by petrolatum gauze. The wound was sealed with an NPWT device at a steady and continuous negative pressure of –80 mm Hg.

The NPWT sponge was changed every 5 days. To prevent skin particles from coming away with the sponge, it was saturated with saline before removal. After the NPWT device was turned off, saline was slowly injected into the foam through the instillation pipe with a syringe to restore the foam to a fully moist state. After 5 minutes, the foam was removed gently and slowly; the petrolatum gauze was left in place. The wound was cleaned with saline to remove exudate, then covered again and NPWT applied for another 5 days. Ten days after the grafting process, the number of surviving skin particles was recorded. One month after grafting, ulcer size was measured again using the aforementioned grids net.

Histologic and cytologic study

Split skin tissue from the rolled edge of a PI was collected for histologic analysis. Hematoxylin-eosin staining was used to examine the structure of the split skin.

The skin sample underwent incubation with 0.25% dispase at 37 °C for 30 minutes, after which the skin sample was rinsed in a buffer solution and manually scraped to wipe off the dermis. After digestion with 0.25% trypsin, as well as drawing up and filtering procedures, keratinocytes were harvested from epidermis and resuspended at a concentration of 5 × 10⁵/mL in a culture flask. Cell viability was determined using the MTT assay with cultured cells from the second passage. Cells were incubated with MTT solution 5 mg/mL for 24 hours and then lysed with dimethyl sulfoxide 150 µL for 10 minutes. Optical density was detected using a microplate reader at 490 nm. This process was repeated for 6 days to determine the cell growth curve.

Histologic and cytologic study of normal skin was also conducted. The normal skin sample was obtained from scalp tissue from a patient treated in the authors’ department that had been discarded as medical waste. Written informed consent was provided to and obtained from this patient.

Patient and wound characteristics

Five patients (1 female, 4 males; mean age, 72.6 years ± 6.1 [standard deviation]) were enrolled in this study (Table 1). Ulcers were located in the hip region in 2 cases and the sacrococcygeal region in 3 cases. The average serum albumin level was 31.4 g/L ± 2.3. Mean duration of ulceration was 30.8 days ± 9.5, and mean ulcer size was 27.8 cm² ± 18.0.

Histologic study

Split skin from the scalp and skin particle from the rolled edge of a PI were obtained and stained with hematoxylin-eosin to show skin structures and cell morphology, respectively. Split skin from the scalp had intact layers and normal arrangement of epidermis cells (Figure 1A). In skin particles harvested from the introversive edge of a PI, no layered structure was observed; however, abundant keratinocytes and hyperkeratosis were observed (Figure 1B).

Cell viability

Second-passage keratinocytes (cultured in vitro) from scalp tissue and tissue from the rolled edge of the PI were tested to determine cell viability. Cell viability (Figure 2) and proliferative ability (Figure 3) were relatively lower in the cells from the rolled edge of the ulcer compared with the cells from the scalp. Statistical significance could not be achieved because of insufficient scalp tissue samples.

Wound size

A total of 45 particles were obtained and transferred to wounds. Ten days after the grafting procedure, 13 skin particles had survived, and new epithelium was observed around those particles. Before grafting, the average wound size was 27.8 cm² ± 17.7. One month after grafting, the average wound size was 16.2 cm² ± 7.3 (Table 2). Although wound size was reduced with treatment, statistical significance could not be achieved because of the lack of a control group.

Case presentation

A 77-year-old male with Alzheimer’s disease who had been bedridden long-term, and who was cared for by a live-in domestic worker, was first seen in the authors’ department in September 2018 (Figure 4A). The patient was unable to communicate and totally dependent. The domestic worker had noticed a PI in the patient’s left hip region 11 days before presentation; the domestic worker had attempted to treat the PI in the home care setting.

At presentation, the patient was evaluated in the emergency department, then transferred to the authors’ department with a high body temperature (38.5 °C). After debridement was performed, necrotic tissue and liquid adipose tissue were removed, deep fascia was exposed, and stealth lacuna was unfolded. Combined treatment with debridement and NPWT resulted in granulation tissue formation over the wound after 3 weeks. Skin particles were harvested, and grafting was performed (Figure 4B). One month after this procedure, 5 surviving skin particles were observed. Two of these particles integrated with each other (Figure 4C).

PI is an economic burden on society and on patients and families worldwide, and it severely reduces patient quality of life. Surgical closure is used to manage grade 4 PIs when long-term conservative treatment is ineffective or in the setting of massive tissue necrosis. Some patients with PI cannot undergo necessary surgery, however, such as those at high risk from general anesthesia or those who cannot tolerate the process of wound cleaning and dressing changes. These patients would benefit from strategies that shorten the duration of conservative treatment.

New methods that speed the wound healing process and minimize patient discomfort should be explored by clinicians and health care providers. Easily performed procedures that are well tolerated by the patient, do not require special devices, and minimize secondary injury should be considered in developing wound repair strategies. Epidermal sheets obtained by suction blister harvesting could be used in wound management. Suction blister roof grafting, which is considered to be among the most effective methods of managing vitiligo, is a minimally invasive technique that could be conducted in the outpatient setting, and it has been reported for use in repairing chronic wounds, including chronic leg ulcers.⁸ Use of the suction blister roof could also stimulate reepithelialization from the wound edge mediated by keratinocyte growth factors.⁹ Wound repair with various sources of cells is another effective method used in many institutions. Transplantation of cultured autologous cell sheets remains widely used in wound healing.¹⁰ A major disadvantage of this technique is the long time interval between biopsy and grafting. Cells harvested from donor sites without culture in vitro could also be used to treat chronic wounds directly. Rashid et al¹¹ achieved promising results with autologous skin cell suspension followed by direct application of the cells to a freshly debrided diabetic foot ulcer with a syringe. However, donor site injury¹²and the need for special devices¹³ should be considered when deciding whether to perform graft harvesting.

In the process of wound healing, the wound edge tends toward introversive growth, which hinders the healing process and should be trimmed off during dressing changes. The current study demonstrated that harvesting skin particles from the rolled edge of a chronic wound is a new donor site for skin grafting. This grafting procedure is well tolerated and effective in the management of PIs, which indicates that it could be applied in people of advanced age with a chronic wound who cannot tolerate a procedure under general anesthesia. NPWT is a popular, well-documented method for the management of various wounds, including PIs, diabetic foot ulcers, and surgical wound dehiscence.^14-16 NPWT promotes wound healing via 4 means: wound contraction, edema reduction, exudate removal, and promotion of cellular proliferation.

In the current study, NPWT was applied for wound preparation, fixation of grafted skin particles, and exudate removal. With a portable NPWT system, this method could be carried out in a wound clinic,¹⁷ and the patient could be released immediately after the procedure and continue the therapy at home until the day of dressing change.

The survival rate of the skin particles was low in the current study. A total of 45 particles were obtained and transferred to ulcers. Ten days after the grafting procedure, 13 skin particles survived (28.9%), and new epithelium was observed around these particles. There are several reasons for graft failure, such as movement of the grafting skin particles caused by the initial replacement of NPWT after skin grafting. Bacterial colonization of the wound, such as Staphylococcus aureus, may cause graft failure. After all, thorough debridement could not be conducted in the inpatient setting without proper anesthesia. During the grafting procedure, some skin particles may be placed incorrectly, that is, without maintaining orientation with the dermal side down. Unlike in micro-skin grafting, the skin particles evaluated in the current study must be kept dermal side down to achieve blood supply from the wound bed. Other factors influence the survival rate of skin particles, and additional studies are needed to analyze these factors to enhance the survival rate of skin particles.

This study has several limitations, including insufficient samples and lack of a control group. Patients with a single PI are relatively rare at the authors’ hospital, and it was difficult to enroll a sufficient number of participants to conduct this feasibility study. A prospective cohort study with more participants should be considered to evaluate this method and draw clinically significant conclusions. The low survival rate of skin particles may impede the extensive application of this method in medical institutions and wound clinics. To accelerate the reepithelialization process, this process could be repeated 1 month after the first grafting procedure to increase the number of surviving skin particles.

The results of this study showed that skin particles harvested from the rolled edge of PIs could survive on the granulation tissue surface and promote wound reepithelialization. This surgical procedure is safe, does not require hemostatic treatment, and can be performed at the bedside without anesthesia. Patients with other types of chronic wounds (eg, diabetic foot ulcers, vascular ulcers) may also benefit from this method.