Biomedical subjects
Publications and source records attributed to A F Falabella.
A relatively recent option for treating leg ulcers that have lasted longer than a month is to use living bilayered skin equivalent alongside cornerstone compression therapy. This article discusses Graftskin and considers its practical use.
The use of skin substitutes to treat acute and chronic wounds should continue to increase as newer products are developed. The goals for the future are to eliminate the need for autografting, eliminate the risk for transmission of disease, improve the shelf life and simplify storage requirements, improve cosmetic outcomes, and reduce cost. A number of researchers are also looking to incorporate gene therapy into skin substitutes.
Tissue-engineered skin is a significant advance in the field of wound healing and was developed due to limitations associated with the use of autografts. These limitations include the creation of a donor site which is at risk of developing pain, scarring, infection and/or slow healing. A number of products are commercially available and many others are in development. Cultured epidermal autografts can provide permanent coverage of large area from a skin biopsy. However, 3 weeks are needed for graft cultivation. Cultured epidermal allografts are available immediately and no biopsy is necessary. They can be cryopreserved and banked, but are not currently commercially available. A nonliving allogeneic acellular dermal matrix with intact basement membrane complex (Alloderm) is immunologically inert. It prepares the wound bed for grafting allowing improved cultured allograft 'take' and provides an intact basement membrane. A nonliving extracellular matrix of collagen and chondroitin-6-sulfate with silicone backing (Integra) serves to generate neodermis. A collagen and glycosaminoglycan dermal matrix inoculated with autologous fibroblasts and keratinocytes has been investigated but is not commercially available. It requires 3 to 4 weeks for cultivation. Dermagraft consists of living allogeneic dermal fibroblasts grown on degradable scaffold. It has good resistance to tearing. An extracellular matrix generated by allogeneic human dermal fibroblasts (TransCyte) serves as a matrix for neodermis generation. Apligraf is a living allogeneic bilayered construct containing keratinocytes, fibroblasts and bovine type I collagen. It can be used on an outpatient basis and avoids the need for a donor site wound. Another living skin equivalent, composite cultured skin (OrCel), consists of allogeneic fibroblasts and keratinocytes seeded on opposite sides of bilayered matrix of bovine collagen. There are limited clinical data available for this product, but large clinical trials are ongoing. Limited data are also available for 2 types of dressing material derived from pigs: porcine small intestinal submucosa acellular collagen matrix (Oasis) and an acellular xenogeneic collagen matrix (E-Z-Derm). Both products have a long shelf life. Other novel skin substitutes are being investigated. The potential risks and benefits of using tissue-engineered skin need to be further evaluated in clinical trials but it is obvious that they offer a new option for the treatment of wounds.
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BACKGROUND: At present, wound treatment of inherited epidermolysis bullosa (EB) is only supportive. OBJECTIVE: To determine the safety and clinical effects of tissue-engineered skin (Apligraf; Organogenesis Inc, Canton, Mass) in the healing of wounds of patients with different types of EB. DESIGN: An open-label uncontrolled study of 15 patients with EB treated with tissue-engineered skin. Each patient received tissue-engineered skin on up to 2 wounds on each of 3 clinic visits: day 1, week 6, and week 12. They were evaluated 7 (+/- 3) days and 6 weeks after each round of treatment. A quality-of-life survey was administered during week 6. SETTING: University of Miami, Miami, Fla. PATIENTS: Volunteers with EB. MAIN OUTCOME MEASURE: Safety and wound healing. RESULTS: A total of 69 different acute wounds received tissue-engineered skin at the day-1 (24 wounds), week-6 (23 wounds), and week-12 (22 wounds) visits. Overall, 63 wounds (79%) were found healed at the day-7 visit. Of the acute wounds, 82% (51/62) were healed 6 weeks after being treated, 75% (27/36) after 12 weeks, and 79% (11/14) after 18 weeks. Nine chronic wounds were also treated. Four were healed at 6 weeks; however, 7 were still open at the last clinic visit (week 18). There were no signs of rejection or clinical infection and no adverse events related to the tissue-engineered skin. The quality of life for most patients improved after treatment. Compared with patients' recollection of wounds treated with standard dressings, healing was faster and less painful. CONCLUSION: In this series of patients, tissue-engineered skin induced very rapid healing, was not clinically rejected, and was devoid of adverse effects. It was felt by the patients and families to be more effective than conventional dressings for EB wounds.
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.
BACKGROUND: Inherited epidermolysis bullosa (EB) is a mechanobullous disorder. The Dowling-Meara variant, a subtype of EB, is characterized by widespread blister formation that may include the oral cavity and nails. Many patients with the Dowling-Meara phenotype are at increased risk of sepsis and death during infancy. The treatment of EB is generally supportive. The tissue-engineered skin used (Apligraf) is a bilayered human skin equivalent developed from foreskin. It is the only Food and Drug Administration-approved skin equivalent of its kind. It is approved for the treatment of venous ulcers of the lower extremities. It has also been used to treat acute wounds, such as graft donor sites and cancer excision sites. OBSERVATION: To our knowledge, we describe the first case in which a newborn with EB, Dowling-Meara variant, was treated with bilayered tissue-engineered skin. The areas treated with the tissue-engineered skin healed faster than the areas treated with conventional therapy. Most of the areas treated with tissue-engineered skin have remained healed, without developing new blisters. These areas appear to be more resistant to trauma. CONCLUSIONS: Our early success with tissue-engineered skin in this patient may have a significant impact on the future treatment of neonates with EB simplex. Future studies are needed to determine if the beneficial effects of tissue-engineered skin are reproducible in other neonates with EB simplex and in patients of all ages with different subtypes of EB.
BACKGROUND: Elase is a widely used ointment consisting of a combination of 2 proteolytic enzymes, fibrinolysin and desoxyribonuclease (DNAse). It is said to promote debridement of necrotic and purulent debris from skin ulcers. OBJECTIVE: Our purpose was to assess the efficacy and safety of this ointment and its components in the treatment of chronic ulcers of the lower extremity. METHODS: This was a double-blind, randomized, prospective study of 84 patients with leg ulcers exhibiting necrotic and purulent debris, who were treated for 21 days with twice-daily applications of the ointment, fibrinolysin, DNAse, or who received the ointment vehicle (placebo). We assessed 6 efficacy features: ulcer size, purulent exudate, necrotic tissue, erythema, pain, and overall condition of the lesion at days 8, 15, and 21 after initiation of treatment. We also assessed the frequency of adverse effects. RESULTS: All treatments produced some improvement in the efficacy parameters and overall condition of the ulcers by week 3, but no statistically significant difference was found when compared with placebo. No serious adverse effects were noted. A later retrospective reanalysis of the data found a statistically significant reduction of purulent exudate only at days 3 and 7 of treatment in the group treated with the complete ointment, but not in the other features. CONCLUSION: The proteolytic ointment provides no long-term clinical benefit in reducing purulent exudate, pain, erythema, necrotic tissue, or overall condition of chronic leg ulcers when compared with either of its two components or placebo.
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Currently wound treatment options of amputation stumps due to purpura fulminans include healing by secondary intention from wound debridement, split-thickness skin grafting, tissue and muscle flaps, plantar skin free transfer, skin expansion, artificial skin, and hyperbaric oxygen therapy. We saw a 6-month-old girl with purpura fulminans as a complication of meningococcemia. She developed necrosis of the distal extremities resulting in bilateral amputation of the lower limbs. Shortly thereafter the leg stumps also became necrosed and she underwent unsuccessful split-thickness grafts of lower limb ulcers. The patient's difficult-to-heal wounds made her an excellent candidate for treatment with tissue-engineered skin. At 10 months of age, this was applied to her previously nonhealing wounds. The tissue-engineered skin induced rapid healing of the patient's chronic amputation stump ulcers and provided her with substantial pain relief. In conclusion, tissue-engineered skin appears to be a potential beneficial treatment for chronic wounds in children with nonhealing amputation stumps.