Methods for promoting healing of skin resurfacing wounds

Details Methods for promoting healing of skin resurfacing wounds Methods for promoting healing of skin resurfacing wounds

1999-10-19

2004-03-30

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Web, sheet or filament bases; compositions of bandages; or...

C424S444000, C424S445000, C424S449000

Reexamination Certificate

active

06713084

ABSTRACT:

FIELD OF THE INVENTION
The invention involves methods of using sheets of cultured epithelial cells to promote healing of skin resurfacing wounds.
BACKGROUND OF THE INVENTION
Removal of superficial skin features has been accomplished previously by procedures such as dermabrasion and chemical peels using acids or other caustic agents such as phenol. These procedures remove portions of the outer and middle layers of the skin, the epidermis and dermis, to remove wrinkles, discolorations, scars, roughness and other features of damaged skin. More recently, short-pulse or rapid scanning lasers (e.g. CO
2
lasers, excimer lasers) have been used for the same purpose. Whereas dermabrasion and chemical peels can result in scarring, discoloration and/or changes in the smoothness of the treated skin relative to surrounding skin, laser treatment typically yields removal of the unwanted skin feature without residual scarring or bleeding.
One of the difficulties which accompanies laser skin resurfacing is the lengthy and often painful post-treatment period. After the laser treatment, ointments and dressings are applied to the wound site to lessen drying of the treated skin and promote healing of the wound. Dressings must be changed often, because the treated skin oozes for 7-14 days following treatment (Arndt and Thomas, Harvard Health Letter, 21:4-5 (1996)). To alleviate the pain associated with the laser resurfacing and to foster healing, patients must perform a series of washes and soaks of the wound site, and then apply additional ointments and dressings to the wound site. Such repetitive treatment of the wound site is painful and inconvenient for the patient, and if not performed properly, increases the risk of infection.
Thus, there exists a need for a procedure which will reduce the need for a patient's self-treatment treatment of the laser wound site. Further, there is a need for a treatment of laser skin resurfacing wound sites that will promote faster healing of the wound, lessen pain and reduce the possibility of infection of the wound site. Additionally, there is a need for a treatment which need not be changed while the skin resurfacing wound heals.
Sheets of cultured epithelial cells can be used as replacements for human skin autografts and allografts. Indications for use of cultured epithelial cell sheets include those for which traditional skin autografts are used, including large surface area burns and chronic skin ulcers. As substitutes for allografts, sheets of cultured epithelial cells also are used for, inter alia, healing of split-thickness autograft donor sites (see, e.g., EP 0 296 475, Cancedda et al.; PCT/AUS91/03582, Tubo et al.)
SUMMARY OF THE INVENTION
The present invention provides methods for promoting healing of wounds which result from skin resurfacing procedures by laser surgery to remove or alter superficial features of the skin. The methods promote faster healing of skin resurfacing wounds relative to prior art methods of healing such wounds. The methods also reduce pain and complications associated with such wounds. The methods involve the application to the skin of sheets of cultured cells.
According to one aspect of the invention, a method for promoting healing of a skin resurfacing wound is provided. The method involves applying a sheet of cultured epithelial cells to the wound of a patient in need of such treatment. Preferably, the sheet substantially covers the wound. The wound is a laser induced wound from a laser skin resurfacing treatment.
In certain embodiments, the sheet of cultured epithelial cells is a preserved sheet. Preferably, the preserved sheet of cultured epithelial cells is dried or frozen. If the preserved sheet of cells is frozen, then it is thawed prior to direct application to the wound. If the preserved sheet of cells exists in a dry state, then it can be applied to the wound after rehydration or applied directly to the wound without prior rehydration, the dried cells rehydrating at the wound site.
In other embodiments, the sheet of cultured epithelial cells is disposed on a backing. The backing provides structural support to the sheet of cells during the step of applying the sheet to the wound. Preferably, the backing is a gauze mesh, but also could be a hydrocolloid, a Teflon sheet, or a collagen matrix. The method optionally provides for covering the applied sheet of cultured epithelial cells with a dressing.
In still other embodiments, the cultured epithelial cells are attached to a substratum or mixed with a gel. Preferably, the substratum is selected from the group consisting of microbeads, hyaluronic acid, collagen, fibrin glue and polymers.
The invention also involves the use of a sheet of cultured epithelial cells in the preparation of a medicament for treating a laser skin resurfacing wound. The sheet of cultured epithelial cells provides, among other things, a covering to prevent dehydration, cell-cell contact between the surface of the sheet of cultured epithelial cells and the skin, and factors released by the sheet of cultured epithelial cells which promote healing.
The invention also involves a cosmetic treatment of skin. In a first step, the skin is treated by lasar surgery to remove or alter superficial features of the skin. In a second step, the lasar skin resurfacing wound created by the lasar treatment then is covered with a sheet of cultured epithelial cells.
These and other aspects of the invention are described in greater detail below.
DETAILED DESCRIPTION OF THE INVENTION
The invention involves methods of promoting healing of a laser skin resurfacing wound. The methods involve the application to the laser skin resurfacing wound of a sheet of cultured epithelial cells. Preparation of such a sheet of cultured epithelial cells is disclosed, for example, in PCT Patent Application PCT/US95/14648. By “applying” is meant placing the sheet of cultured epithelial cells upon the wound and, optionally, covering the sheet of cultured epithelial cells with a dressing. Thus, applying a sheet of cultured epithelial cells is performed according to any standard medical procedure for applying a dressing to a wound. If necessary, after applying it, one can attach the sheet of cultured epithelial cells to the tissue surrounding the laser skin resurfacing wound by means of a dermatologically-acceptable adhesive, for instance a biological adhesive such as fibrin glue.
The wound to be treated is created during the process of skin resurfacing by laser irradiation. Skin can be “resurfaced” by the use of different lasers, such as a short pulse or rapid scanning carbon dioxide laser, or an excimer laser. Other lasers useful for performing skin resurfacing will be known to one of ordinary skill in the art. By “resurfacing” is meant the removal of selected portions of the epidermis and underlying tissue, to achieve a desired removal of unwanted skin features. The laser emits a beam of light which imparts energy to the epidermis in a highly localized fashion. The portion of the skin contacted by the laser beam is vaporized, thus removing unwanted features such as wrinkles, discolorations, and other surface irregularities. The laser skin resurfacing wound does not extend to the deeper, unvaporized layers of the skin remaining at the site of laser treatment. By migration and proliferation of cells originating in hair follicles or sweat glands in deeper layers, a new upper layer of skin lacking the unwanted surface features is generated.
Traditional therapy for promoting healing of the laser skin resurfacing wound includes the application of ointments and nonbiological dressings, which must be changed frequently. The newly generated layer of skin grows and differentiates underneath the dressing to fill in the laser wound.
The application of a sheet of cultured epithelial cells enhances the healing process by providing to the wound growth factors, extracellular matrix components and other wound healing agents. The present invention facilitates the application of a physiologically relevant amount of growth factors, extracellular matrix c

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