Skin grafts as pharmacological agents: pre-wounding of the donor site

Skin Microcolumns as a Source of Paracrine Signaling Factors

Objective: We recently developed the approach of using “microcolumns” of autologous full-thickness skin tissue for wound repair. The small size of these micro skin tissue columns (MSTCs, ∼0.5 mm in diameter) allows donor sites to heal quickly without scarring. Treatment with MSTCs significantly accelerate wound healing, and suppled various skin cell types and skin structures to replenish the wound volume. This technology is now starting clinical use. In this study, we investigate whether MSTCs may also influence wound healing by releasing soluble signaling factors.

Approach: Freshly harvested MSTCs were incubated in culture medium for 24 h. The conditioned medium was collected and tested for its effects on migration and proliferation of human dermal fibroblasts, and its ability to induce tube formation by human umbilical vein endothelial cells (HUVECs). Proteins released into the conditioned medium were characterized by multiplex enzyme-linked immunosorbent assay (ELISA), and compared with medium conditioned by an equivalent mass of intact full-thickness skin.

Results: MSTC-conditioned medium increased fibroblast migration and proliferation, as well as HUVEC tube formation. MSTCs released many soluble factors known to play prominent roles in wound healing. A subset of proteins showed significantly different release profiles compared with intact full-thickness skin.

Innovation: The technology for harvesting and using MSTCs to augment wound healing was recently developed as an alternative to conventional autologous skin grafting. This study shows that MSTCs could also function as “cytokine factories.”

Conclusion: In addition to supplying autologous cells to repopulate the wound volume, MSTCs can also function as a source of growth factors and cytokines to further enhance wound healing.

Hair follicle-containing punch grafts accelerate chronic ulcer healing: A randomized controlled trial

BACKGROUND

A prominent role of hair follicle-derived cells in epidermal wound closure is now well established but clinical translation of basic research findings is scarce. Although skin punch grafts have been used as a therapeutic intervention to improve healing of chronic leg ulcers, they are normally harvested from nonhairy areas, thus not taking advantage of the reported role of the hair follicle as a wound-healing promoter.

OBJECTIVE

We sought to substantiate the role of hair follicles in venous leg ulcer healing by transplanting hair follicle-containing versus nonhairy punch grafts.

METHODS

This was a randomized controlled trial with intraindividual comparison of hair follicle scalp grafts and nonhairy skin grafts transplanted in parallel into 2 halves of the same ulcer.

RESULTS

Ulcer healing measured as the average percentage reduction 18 weeks postintervention was significantly increased (P = .002) in the hair follicle group with a 75.15% (SD 23.03) ulcer area reduction compared with 33.07% (SD 46.17) in the control group (nonhairy grafts).

LIMITATIONS

Sample size was small (n = 12).

CONCLUSION

Autologous transplantation of terminal hair follicles by scalp punch grafts induces better healing than punch grafts harvested from nonhairy areas. Hair punch grafting is a minimally invasive surgical procedure that appears to be effective as a therapeutic tool for chronic venous leg ulcers.

A Clinical Investigation on the Characteristics and Outcomes of Treating Chronic Lower Extremity Wounds using the TissueTech Autograft System

The application of tissue engineering technology to wound healing has resulted in the development of a number of “living skin equivalents.” These have become a viable option in the treatment of chronic, nonhealing wounds. Such wounds present a major cost burden as well as increased morbidity and mortality. Unique among skin tissue engineering technology is the TissueTech autograft system, as it incorporates an autologous dermal substitute—Hyalograft® 3D—and an autologous epidermal replacement, Laserskin® autograft. Each includes a matrix of a hyaluronic acid ester to promote cellular migration and graft take.

Punch grafting of chronic ulcers in patients with laminin-332-deficient, non-Herlitz junctional epidermolysis bullosa

BACKGROUND

Epidermolysis bullosa (EB) is a genetic, heterogeneous, trauma-induced blistering disease. Patients with laminin-332-deficient non-Herlitz junctional EB (JEB-nH) can have impaired wound healing witnessed by persistent, small, deep ulcers on the hands and feet that adversely affect the quality of life.

OBJECTIVE

We sought to present the results of punch grafting in patients with laminin-332-deficient JEB-nH, and to discuss its therapeutic value.

METHODS

Retrospective analysis of the Dutch EB Registry revealed 4 patients with laminin-332-deficient JEB-nH who were treated with punch grafting. Punch grafting was performed according to protocol, and the patients were followed up.

RESULTS

In the past 10 years we have treated 23 ulcers in 4 patients with JEB-nH using punch grafting without any complications or adverse effects. The ulcers had on average persisted 6 years before treatment. Healing rate after punch grafting was 70% (n = 16), with a mean healing time of 2 months. Thirty percent (n = 7) of the treated ulcers did not completely heal, but did show improvement. The recurrence rate after 3 months was 13% (n = 2), and was a result of renewed blistering.

LIMITATIONS

Limitations of the study are the retrospective design, small number of patients, absence of a control group, and follow-up and ulcer measurement that were not standardized.

CONCLUSIONS

Punch grafting can be used as a first-line treatment in small persistent ulcers in patients with JEB-nH. The method is easy, is inexpensive, has little risk of complications, and results in significant healing rates and improvement in quality of life.

Spontaneous clostridial myonecrosis after pregnancy - emergency treatment to the limb salvage and functional recovery: a case report

Clostridial myonecrosis (CM) is a rare, life threatening necrotizing infection of a skeletal muscle caused by Clostridium perfringens in the majority of cases. The diagnosis may be difficult because of few diagnostic and cutaneous signs early in its course. Standard therapy involves surgical debridements of a devitalized tissue and high-dose organism-specific antibiotic therapy. The hyperbaric oxygen has also showed its usefulness in the treatment of these infections. Autograft systems as tissue replacement, based on bioengineered materials, have been demonstrated to be safe and effective treatments for chronic wounds and a suitable physiotherapy is recommended for the recovery of functional impairments of upper extremities. We present a rare case of CM of right upper limb treated with a combination of standard treatments and new techniques.

Two-Step Autologous Grafting Using HYAFF Scaffolds in Treating Difficult Diabetic Foot Ulcers: Results of A Multicenter, Randomized Controlled Clinical Trial With Long-Term Follow-up

This study evaluated the efficacy and tolerability of an autologous tissue-engineered graft—a 2-step HYAFF autograft—in the treatment of diabetic foot ulcers compared with standard care. In all, 180 patients with dorsal or plantar diabetic foot ulcers (unhealed for ≥1 month) were randomized to receive Hyalograft-3D autograft first and then Laserskin autograft after 2 weeks (n = 90; treatment group) or nonadherent paraffin gauze (n = 90; control group). Efficacy and adverse events were assessed weekly for 12 weeks, at 20 weeks, and at 18 months. The primary efficacy outcome was complete ulcer healing at 12 weeks. Wound debridement, adequate pressure relief, and infection control were provided to both groups. At 12 weeks, complete ulcer healing was similar in both groups (24% of treated vs 21% controls). A 50% reduction in ulcer area was achieved significantly faster in the treatment group (mean 40 vs 50 days; P = .018). Weekly percentage ulcer reduction was consistently higher in the treatment group. At 20 weeks, ulcer healing was achieved in 50% of the treated group as compared with 43% of controls. Dorsal ulcers had a 2.17-fold better chance of wound healing per unit time following autograft treatment ( P = .047). In a subgroup with hard-to-heal ulcers, there was a 3.65-fold better chance of wound healing following autograft treatment of dorsal ulcers ( P = .035). Adverse events were similar in both groups. The study results demonstrated the potential of this bioengineered substitutes to manage hard-to-heal dorsal foot ulcers.

Standardised method of surgical treatment of chronic leg ulcers

Healing and recurrence rates were compared in leg ulcers of different aetiology in 385 patients with 406 chronic leg ulcers. Standard treatment was excision of the ulcer followed by meshed split-skin grafting and correction of superficial venous insufficiency in the area. The median age of the patients was 75 years (range 16-95). After one year 345 patients with 357 leg ulcers were alive. Overall healing rate was 64% (227 in 357 legs) after one year. The best results were achieved in traumatic ulcers (31 in 36 ulcers) and worst for the arterial ulcers (4 in 20 ulcers). Recurrence rate in venous and venous/ischaemic ulcers was 14% (33 in 235 legs) and 8% (n=3) in the traumatic ulcers. Vasculitic ulcers tend to recur 59% (n=10), but the graft does relieve pain.

Bilayered bioengineered skin substitute (Apligraf): a review of its use in the treatment of venous leg ulcers and diabetic foot ulcers

The bilayered bioengineered skin substitute (BBSS) [Apligraf] is used for the treatment of venous leg ulcers and diabetic foot ulcers. It has an epidermal layer formed from human keratinocytes and a dermal layer composed of human fibroblasts in a bovine type I collagen matrix. BBSS does not contain any antigen-presenting cells such as Langerhans cells, dermal dendritic cells, endothelial cells or leucocytes. In clinical trials, there was no evidence of clinical rejection and immunological tests indicated no humoral or cellular response to the keratinocytes or fibroblasts of BBSS. Further clinical trials are required to identify the exact mechanism of action of BBSS in chronic wounds. BBSS plus compression therapy was well tolerated and was superior in efficacy to compression therapy alone in a multicentre, randomised trial in patients with venous leg ulcers. At 6 months' follow-up, complete wound healing occurred in 63 versus 49% of patients and the median time to wound closure was 61 versus 181 days. In a subgroup of patients with hard-to-heal ulcers (>1 year's duration), wound healing was achieved in significantly more patients (47 vs 19%) and the median time to wound healing was significantly shorter (181 days vs not attained). In a multicentre, randomised trial, BBSS was well tolerated and effective in patients with full-thickness neuropathic diabetic foot ulcers. Ulcer healing occurred in significantly more patients (56 vs 38%) and the median time to wound healing was shorter (65 vs 90 days) with BBSS than with saline-moistened gauze at 12 weeks' follow-up. Patients in both groups also received standard diabetic foot care. The cost effectiveness of BBSS in patients with chronic ulcers has yet to be examined in well designed, prospective clinical trials. However, according to a modelled analysis incorporating data from a multicentre randomised trial, BBSS was cost effective in patients with hard-to-heal venous leg ulcers. The average annual medical cost of managing patients with ulcers of >1 year's duration was estimated to be 20,041 US dollars per patient treated with BBSS plus compression therapy and 27,493 US dollars per patient treated with compression therapy alone (1996 costs).

CONCLUSIONS

Clinical trials have shown that BBSS in conjunction with standard compression therapy was effective and well tolerated in patients with venous leg ulcers, especially patients with ulcers of >6 months' duration or that extended to the subcutaneous tissue. In addition, BBSS in conjunction with standard diabetic foot care was effective and well tolerated in patients with full-thickness neuropathic diabetic foot ulcers. BBSS represents a useful adjuvant to standard ulcer therapy in patients with venous leg ulcers or full-thickness neuropathic diabetic foot ulcers that do not respond to conventional ulcer therapy.

Skin Grafting of Venous Ulcers: A Review of its Current Role

As a therapeutic option, grafting of venous ulcers has not been very successfully received despite the different types of grafting methods. Currently, there are only a few controlled randomized trials offering clear guidance to clinicians. The development of artificially bioengineered skin constructs has led to a renewed interest in wound bed preparation, and preliminary successes suggest that the role of skin grafting could be studied in the current context.

Skin grafting

No longer an option of last resort, skin grafting has become a technique that is routinely and sometimes preferentially considered as skin replacement for burns, chronic ulcers, and skin defects after cutaneous surgical procedures. When selected as the best alternative for wound closure, autologous skin grafts are commonly considered the gold standard. Availability of autologous grafts is a major obstacle, however, and the search for a manufactured skin replacement has continued. In cases in which autologous grafts cannot be performed, skin substitutes have become an attractive alternative.

Involvement of keratinocyte activation phase in cutaneous graft healing: comparison of full-thickness and split-thickness skin grafts

BACKGROUND

Little is known about keratinocytic activation in the graft take and healing process.

OBJECTIVE

To investigate the clinical and molecular differences between pure epidermal sheet graft (PESG), split-thickness skin graft (STSG), and full-thickness skin graft (FTSG).

METHODS

Three different thickness skin grafts (PESG, STSG, and FTSG) were performed onto three kinds of porcine wounds: shallow, deep, and full. Graft take, contraction, and Ki-67 and beta1 integrin expression in epidermis were studied.

RESULTS

All grafts took well. As expected, full wounds covered by PESG and STSG contracted more than those covered by FTSG, whereas shallow wounds covered by FTSG contracted more than those covered by STSG. No difference in contracture was observed among deep wounds covered by PESG, STSG, and FTSG. Up-regulation of Ki-67 and beta1 integrin expression was greater in PESG and STSG, compared with little expression in FTSG.

CONCLUSION

The keratinocytic activation phase may occur both in the STSG and PESG healing process, as well as serum imbibition, inosculatory, and revascularization phases.

Pinch graft skin transplantation for leg ulcers in primary care

Pinch grafting offers an alternative approach to conventional management of chronic leg ulcers, and is particularly well suited for venous and diabetic ulcers. Relevant literature from 1872-1998 was reviewed. The method of pinch grafting is described here in detail, and is illustrated by two case reports. Since pinch grafting hastens the healing of granulating wounds, is easy to perform and does not require strict immobilisation, a revival of the method, with adaptation for primary care, should be encouraged.

Treatment of leg ulcers with split skin grafts: early and late results

Sixty patients (mean age 73.5 years) with 88 leg ulcers that had not responded to conservative treatment had split skin grafts applied at the Department of Plastic Surgery, Linköping, Sweden. Of 51 venous leg ulcers 45 (88%) healed after a mean of 15 days (range 5-30); and 13 (62%) of the 21 arterial ulcers healed after a mean of 18 days (range 8-30). Additional skin grafting was done on nine of the venous and on three of the arterial ulcers. Twenty-two (49%) of the healed venous ulcers recurred after a mean of four months while only two (15%) of the healed arterial ulcers recurred after a mean of 10 months. At late follow up after a mean of four years 18 of the patients were dead and 10 had had the leg in question amputated. Of the 34 patients still alive who had not had amputations, 31 were investigated at open ward or interviewed by telephone and 23 patients were examined with colour duplex scan. Seven of these patients had open leg ulcers. At duplex scan six patients had no venous or arterial insufficiency that could cause a leg ulcer. Of 16 patients with venous insufficiency 10 patients had only an inadequate superficial system. The mean cost for treating one leg ulcer by skin grafting is estimated at SEK 89000 (US$11125). We conclude that leg ulcers often heal with skin grafting but that venous ulcers often recur. To reduce the recurrence rate we suggest a better preoperative aetiological evaluation and improved postoperative treatment with a compression bandage.

Characterization of epidermal wound healing in a human skin organ culture model: acceleration by transplanted keratinocytes

Few data are available on early regeneration of human epidermis in vivo. We have established a supravital skin organ culture model for epidermal wound healing by setting a central defect (3 mm diameter) in freshly excised skin specimens and culturing under air exposure. Re-epithelialization was followed for up to 7 d by histology and immunohistologic analysis of various markers for differentiation and proliferation. In 12 of 19 cases (63%; 5% fetal calf serum) or six of 21 cases (29%; 2% fetal calf serum), the wounds were re-epithelialized spontaneously after 7 d. After transplantation to the wounds of 1-2 x 10(6) dissociated allogenic cultured epidermal or about 1 x 10(6) autologous outer root sheath keratinocytes, 18 of 21 cases (86%; 5% fetal calf serum) or 17 of 21 cases (81%; 2% fetal calf serum) were healed within the same period. Histologically, early neoepithelium (3 d) was disordered after keratinocyte transplantation, whereas later (7 d) it had gained a more ordered stratification, exhibiting a thin discontinuous granular and a compact horny layer. At this stage, not only hyperproliferative (CK 6) but also, abundantly, maturation-associated cytokeratins (CK 1, CK 10) were detected immunohistochemically. Analyses of regenerated epidermis after transplantation of (i) keratinocytes labeled in vitro with BrdU and (ii) heterosexual keratinocytes by immunohistochemistry and fluorescence in situ hybridization for the Y chromosome, respectively, clearly showed that external keratinocytes are physically integrated into the regenerated epidermis and extendedly contribute to its formation. The data presented here demonstrate improvement and acceleration of epidermal re-epithelialization by transplantation of keratinocytes.

The development of bioengineered skin

Driven by the need for donor tissue for patients suffering from extensive burns, alternatives to autologous and cadaver-derived tissue have been under development for the past 20 years. Unilayered and bilayered models representing the skin's epidermal and/or dermal components have been developed using both cells and matrix materials. In addition to their use in patients with extensive burns, trials using these products on refractory and challenging patients with both acute and chronic wounds have led to the commercial availability of some of these products.

Tissue engineering and the development of Apligraf, a human skin equivalent

In recent years, skin grafting has evolved from the initial autograft and allograft preparations to biosynthetic and tissue-engineered living skin replacements. This review details the pioneering work of numerous investigators that led to the following precursors of tissue-engineered skin replacement: cultured autologous keratinocyte grafts, cultured allogeneic keratinocyte grafts, autologous/allogeneic composites, acellular collagen matrices, and cellular matrices. It also discusses the rationale for the development of the newer products and describes the technical advances leading to the development of Apligraf, a tissue-engineered human skin product.

Chronic wounds

Skin ulcers are the most common chronic wounds. Current management principles and theories of causation of the most common ulcers--pressure, diabetic, and venous--are described. Issues related to occlusive dressings, compression dressings, topical antimicrobials, debridement, growth factors, grafting, and bioengineered tissue therapy are discussed. Special emphasis is placed on regulatory concerns.

Split-thickness skin grafting for lower extremity ulcerations

BACKGROUND

Leg ulcers are often refractory to conservative treatment, often mandating the use of skin grafting.

OBJECTIVES

This review article discusses skin grafts, with special emphasis on split-thickness grafts for lower extremity ulcerations.

METHODS

Historical background, proposed mechanisms of action, biology of skin grafts, techniques for skin grafting, and results after grafting are discussed separately.

RESULTS

Skin grafting has been performed for centuries. However, how skin grafts work, whether solely as tissue replacement or, additionally, as a stimulus for healing, is still not fully known. After placement, the grafted skin proceeds through a series of phases by which nutrients are supplied and neovascularization occurs. Adherence to the ulcer bed through interactions between the graft and the ulcer bed appear critical. When meshed split-thickness skin grafts are properly performed, success rates from 50% to 75% have been reported for refractory venous ulcers.

CONCLUSIONS

Better understanding of the biologic and clinical aspects of skin grafting should lead to improved patient care.

LEARNING OBJECTIVES

After studying this article, participant should be able: 1. To understand the various types of skin grafts. 2. To learn the potential mechanisms of action of how skin grafts work. 3. To appreciate the benefit of skin grafts for lower extremity ulcerations.