Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Hair or skin
Reexamination Certificate
1999-08-02
2004-05-11
Falk, Anne-Marie (Department: 1632)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Hair or skin
C424S422000, C424S425000, C623S011110, C623S015110
Reexamination Certificate
active
06733530
ABSTRACT:
REFERENCE TO SPONSORSHIP
This invention was made under the joint sponsorship of the Chinese University of Hong Kong of Shatin, Hong Kong SAR, and the Hospital Authority, also known as the Prince of Wales Hospital of Shatin, Hong Kong SAR.
BACKGROUND OF THE INVENTION
This invention relates to the cultivation of keratinocytes and dermal fibroblasts on a biosynthetic membrane and subsequent engraftment of this type of membrane on the neodermis of artificial skin with particular application to humans. This invention also relates to fabricated graft materials.
Prompt wound coverage for protection and stabilization is essential for the treatment of burns. The 3T3 cell-feeder layer technique developed by Rheinwald and Green in the 1970s is the standard method for cultivation of autologous epidermal autograft or so-called cultivated epidermal autograft material (“CEA”). A small piece of native skin from the patient can be cultured and expanded to 500 times or more in size within 3-4 weeks. However, the lack of dermis and the fragility of the cultured graft often result in unpredictable grafting success rates ranging from 0%-80%, as reported by Tompkins et al. (1992) and Herzog et al. (1991).
ALLODERM™ and INTEGRA™ human skin substitutes are two currently popular examples of human skin substitute commercially available in the market. INTEGRA™ artificial skin, a brand of artificial skin is sold by Integra LifeScience Corporation of New Jersey, USA, and has been approved by FDA for use in the USA since 1996. Artificial skin is a bilayer biosynthetic sheet comprising porous collagen-glycoaminoglycan integrated with a thin silicone membrane as an outer layer. The use of artificial skin such as INTEGRA™ artificial skin as a biocompatible a cellular dermal replacement in deep and full-thickness burn wounds is well known.
It has been observed that within about 14 to 21 days following the grafting of INTEGRA™ artificial skin, there is full vascularization of the neodermis formed in the INTEGRA™ artificial skin. Thereafter an ultra thin split thickness skin graft must be harvested from a donor site in order to cover the neodermis immediately after the silicone membrane is removed. Substantial research effort has been undertaken in the past to determine the possibility of reliably grafting CEA on the neodermis, since an effective combination of CEA and INTEGRA™ artificial skin should eliminate the second operative stage, the associated pain and scaring, as well as a need for a second donor site, which may not be available in extensively burned patients. If the grafted CEA does not ‘take’ on the neodermis of INTEGRA™ artificial skin after the silicone membrane is peeled off, it can be replaced by another CEA. Whereas, in the conventional application of INTEGRA™ artificial skin, another split thickness autograft must be harvested from a second or even a third donor site. There have been very limited initial anecdotal reports on experience with such a combination technique, such as Sheridan et al. 1999 and Pandya et al. 1998. At the 10th Congress of International Society For Burn Injuries, November 1998 in Israel, the difficulties with the conventionally cultured graft anchoring onto the neodermis of INTEGRA™ artificial skin were addressed. The exact reasons for such difficulties remain unknown.
LASERSKIN™ artificial skin material is a thin and pliable biosynthetic membrane comprising a 100% benzyl esterified hyaluronic acid derivative suitable for use as a substratum in the growth of skin cells. The recommendation of the manufacturer is to seed human keratinocytes on LASERSKIN™ artificial skin preseeded with irradiated 3T3 cells as feeder layer. When following the manufacturer's recommendation, it was found that, after the initiation of the formation of keratinocyte colonies, the xenogenic 3T3 cells growing on the LASERSKIN™ artificial skin were less likely to be washed away than those growing on a culture dish as in the conventional Green's method during each flushing procedure with phosphate-buffered saline. It is believed that the remaining 3T3 cells or debris might have sensitized the host to xenogenic antigen resulting in undesired late graft rejection. What is needed is a cultivation and engraftment procedure with a biocompatible, durable human skin substitute.
Related References
The following references, not all of which are prior art for the purposes of a patent application, are hereby made of record and incorporated herein by reference for the purposes described in this text:
1) Rheinwald J, Green H. “Serial cultivation of strain of human epidermal keratinocytes: The formation of keratinizing colonies from single cells.” Cell 1975; 6: 331-344.
2) Tompkins R G, Burke J F. “Burn wound closure using permanent skin replacement material.” World J Surgery 1992; 16: 47-52.
3) Herzog S R, Meyer A, Woodley D, Peterson H D. “Wound coverage with cultured autologous keratinocytes: Use after burn wound excision, including biopsy follow-up.” J Trauma 1991; 28: 195-1999.
4) Yannas I V, Burke J F, Orgill D P, Skrabut E M. “Wound tissues can utilize a polymeric template to synthesize a functional extension of skin.” Science 1982; 215: 174-176.
5) Heimbach D, Letterman A, Burke J et al. “Artificial dermis for major burns. A multi-center randomized clinical trial.” Ann Surgery 1988; 208: 313-320.
6) Sheridan R L, Heggerty M, Tompkins R G, Burke J F. “Artificial skin in massive burns-results at ten years.” Eur J Plast Surgery 1994; 17: 91-93.
7) Sheridan R L, Tompkins R G. “Skin substitutes in burns.” Burns 1999; 25: 97-103.
8) Pandya A N, Woodward B, Parkhouse N. “The use of cultured autologous keratinocytes with Integra in the resurfacing of acute burns.” Plast Reconst Surgery 1998; 102: 825-828.
9) Hultman C S, Brinson G M, Silitharm S, et al. “Allogenic fibroblasts used to grow cultured epidermal autografts persist in vivo and sensitize the graft recipient for accelerated second-set rejection.” J Trauma 1996; 41: 51-60.
10) Lam P K, King W K, et al. “Development and evaluation of a new composite Laserskin graft” Abstracts of the 10th Congress of International Society For Burn Injuries, Nov. 1-6 1998, Jerusalem, Israel, p. 46.
11) Sato T, Kirimura Y, Mori Y. “The co-culture of dermal fibroblasts with human epidermal keratinocytes induces increased prostaglandin E2 production and cyclooxygenase 2 activity in fibroblasts.” J Investigative Dermatology 1997; 109: 334-339.
12) Pano R J, Rubin J R, Aaronson S A, Mason R. “Keratinocytes growth factor and hepatocyte growth factor/scatter factor are heparin-binding growth factors for alveolar type II cells in fibroblast-conditioned medium.”J Clin Invest 1993; 92: 969-977.
13) Burd DAR, Greco R M, Regauer M T, et al. “Hyaluron and wound healing: a new perspective.” Br J Plast Surgery 1991; 44: 579-584.
14) Feinberg R N, Beebe D C. “Hyaluronate in vasoculogenesis.” Science 1983; 220: 1177-1179.
15) Alman D G. Practical Statistics for Medical Research Chapman & Hall, London 1991 pp. 211, 260-261.
16) Harris P A, Francesco F di, Barisoni D, Leigh I M, Navsaria H A. “Use of hyaluronic acid and cultured autologous keratinocytes and fibroblasts in extensive burns.” Lancet 1999; 353: 35-36.
17) Myers S R, Grady J, Soranzo C, Sander R, et al. “A hyaluronic acid membrane delivery system for cultured keratinocytes: Clinical take rates in the porcine Kerato-Dermal model.” J Burn Care Rehabil 1977; 18: 214-222.
18) Hansbrough J F, Dore C, Hansbrough W N. “Clinical trials of living dermal tissue replacement placed beneath meshed, split-thickness skin grafts on excised burn wounds.” J Burn Care Rehabil 1992; 13: 519-529.
SUMMARY OF THE INVENTION
According to the invention, autologous cultured keratinocytes grown on a biocompatible substratum are engrafted on the neodermis of artificial skin covering a wound. Autologous keratinocytes may be cultivated on a commercially available membrane such as LASERSKIN™ artificial skin (available from Fidia Advanced Biopolymers Ltd., Abano Terme (PD), Italy) following pre-seeding with autologous or allogenic dermal fibroblasts. The
Chan Eric Sun-Yin
Lam Ping Kuen
Chan Eric Sun-Yin
Falk Anne-Marie
Townsend and Townsend / and Crew LLP
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