Surgery – Miscellaneous – Methods
Reexamination Certificate
2000-06-02
2003-12-30
Willse, David H. (Department: 3738)
Surgery
Miscellaneous
Methods
C623S008000, C623S915000, C606S192000, C600S036000
Reexamination Certificate
active
06668836
ABSTRACT:
TECHNICAL FIELD
This invention resides jointly in the fields of surgery and tissue culture and is particularly directed to the expansion of animal tissue from an original, natural size to a larger size, usually with the intention of using the expanded tissue to replace defective tissue in the body of a living patient.
BACKGROUND
Tissue replacement is an essential component of reconstructive surgery after burns, trauma, tumor excision, and correction of congenital anomalies. For example, there are approximately 1 million burns per year in the U.S. alone, which result in about 100,000 admissions to burn units, about ⅓ of which require skin grafting.
The best possible skin available for grafting would be skin from the same patient taken from a donor site elsewhere on the body (referred to as an autograft). Suitable skin graft donor sites, however, are limited not only by body surface area, but can also be affected by previous graft harvest or trauma. There are times, when donor skin is limited and the amount of skin required for grafting is quite large, that sufficient autografts are not available. Because of the importance of the skin in preventing infection, either the donor skin must be used to cover a larger area than it originally covered or some suitable replacement material must be used. Harvesting of multiple skin grafts from the same donor site is often used, but such harvesting requires weeks to months between procedures for new skin to grow on the donor site. It is also a very traumatic technique, since multiple painful operations must be undertaken.
In a similar manner, other tissues also require replacement after traumatic injury, tumor excision, and other medical situations involving tissue loss. Autografts are preferred for muscle, cartilage, tendon, nerve, and other tissue replacement whenever possible in order to reduce host vs. graft immunity issues. Under appropriate circumstances, donor tissues derived from sources other than the recipient are acceptable for both skin and other tissues, but usually only as temporary replacements. For example, in patients suffering from large bums with limited donor skin sites, cadaver allografts are commonly used for temporary skin coverage, but ultimately such allografts are rejected and a permanent autograft is required. In addition, allografts also pose a risk of infection of the recipient by viruses or other disease-causing organisms present in the donor, such as infection by human immunodeficiency virus or hepatitis virus.
Artificial tissues have been developed in order to avoid the problems associated with allografts. For example, to aid in the grafting of skin on patients with limited donor areas, cultured epithelial cells derived from the patient being treated have been utilized in many grafting applications. In general, the cells are used in the form of a monolayer of epithelial cells grown on a culture medium. Preparation of such cultures requires many weeks or months, and the product is quite difficult to handle because of its fragility, even when multiple epidermal cell layers are used to form a multi-layer skin substitute.
Tissue expansion techniques, which were developed as in vivo techniques, have been used in plastic surgery for over a decade and can be helpful in increasing the area of donor tissue. Skin is not the only tissue that can be and has been expanded, although it is the most common. Other tissues have been expanded in surgical and other in vivo situations. Arteries, peripheral nerves, and skin have all been expanded in human clinical trials. Ureter, small bowel, and bladder have been expanded in animal trials.
The techniques used for in vivo tissue expansion are similar for all tissue types and involve mechanically stretching the tissue while the tissue is still attached to the patient's body. For example, by placing an expander subcutaneously and injecting it with saline, skin can be expanded and its surface area increased. This allows reconstruction with local skin after expansion of an adjacent tissue bed.
Background information in the general field of tissue expansion, including techniques suitable for skin grafting and tissue replacement, is available in the patent and scientific literature. A number of exemplary patents and scientific publications are cited below, both as examples of existing technology and to provide additional basis and support for ancillary technology related to the practice of the present invention:
U.S. Pat. No. 5,882,353 entitled “Mechanical tissue expander”
U.S. Pat. No. 5,858,003 entitled “Systems and methods for promoting tissue growth”
U.S. Pat. No. 5,855,588 entitled “Combination dissector and expander”
U.S. Pat. No. 5,788,627 entitled “Cavernosal extension implants”
U.S. Pat. No. 5,776,159 entitled “Combination dissector and expander”
U.S. Pat. No. 5,630,843 entitled “Double chamber tissue expander”
U.S. Pat. No. 5,618,310 entitled “Tissue, expansion and approximation device”
U.S. Pat. No. 5,549,713 entitled “Method for skin tissue expansion”
U.S. Pat. No. 5,507,775 entitled “Tissue expansion and approximation device”
U.S. Pat. No. 5,476,479 entitled “Handle for endoscopic surgical instruments and jaw structure”
U.S. Pat. No. 5,441,540 entitled “Method and apparatus for skin tissue expansion”
U.S. Pat. No. 5,425,760 entitled “Tissue expander apparatus, and methods of constructing and utilizing same”
U.S. Pat. No. 5,158,571 entitled “Tissue expander and method for expanding tissue”
U.S. Pat. No. 5,092,348 entitled “Textured tissue expander”
U.S. Pat. No. 5,005,591 entitled “Self-inflating tissue expander”
U.S. Pat. No. 4,904,267 entitled “Method and device for fixing a joint prosthesis”
U.S. Pat. No. 4,863,469 entitled “Method and apparatus for expanding nerve tissue”
U.S. Pat. No. 4,828,560 entitled “Spring ring tissue expander”
U.S. Pat. No. 4,800,901 entitled “Balloon-type Tissue expansion device”
U.S. Pat. No. 4,643,733 entitled “Permanent reconstruction implant and method of performing human tissue expansion”
U.S. Pat. No. 4,157,085 entitled “Surgically implantable tissue expanding device and the method of its use”
Argenta, “Controlled tissue expansion in reconstructive tissue,” Brit. J. Plas. Surg., 37:520-529 (1984)
Argenta et al., “The Use of Tissue Expansion in Head and Neck Reconstruction,” Ann. Plast. Surg., 11:31-37(1983).
Arons et al., “The surgical applications and implications of cultured human epidermis: A comprehensive review,” Surgery, 111:4-11 (1992)
Carney, “Generation of autograft; the state of the art,” Burns, 12:231-235 (1986).
Chen, “An animal experiment on short gut lengthening,” Chin. Med. J. (Engl.), 110:354-357 (1997).
Gallico, “Biologic Skin Substitutes,” Clinics in Plastic Surgery, 17:519-526 (1990)
Greenwald et al., “Full-Thickness Skin Wound Explants in Tissue Cultures: A Mechanical Evaluation of Healing,” Plastic and Reconstructive Surgery, 90:289-294 (1992)
Kirsner et al, “The Biology of Skin Grafts,” Arch. Dermatol., 129:481-483 (1993)
Liatsikos et al, “Tissue expansion: a promising trend for reconstruction in urology,” J. Endourol., 14:93-96 (2000).
Nanchahal and Ward, “New grafts for old? A review of alternatives to autologous skin,” Brit. J. Plas. Surg., 45:354-363 (1992)
Satar and Atala, “Progressive dilation for bladder tissue expansion,” J. Urol., 162:829-831 (1999).
Stifelman and Hensle, “Ureteral tissue expansion for bladder augmentation: a long term prospective controlled trial in a porcine model,” J. Urol., 160:1826-1829 (1998).
Sung Shin Wee et al., “Continuous versus intraoperational expansion in the pig model,” Plastic and Reconstructive Surgery, 90:808-814 (1992)
A particularly useful advance in the field of tissue expansion was initiated by Dr. Joshua Korman, who developed the first process for in vitro skin expansion in the 1990s. The investigations of Dr. Korman resulted in the issuance of two U.S. patents, U.S. Pat. No. 5,686,303, entitled “Method of Growing Vertebrate Skin In Vitro,” and U.S. Pat. No. 5,914,264, entitled “Apparatus for Growing Vertebrate Skin In Vitro.” The method involves growi
Fields Antony J.
Greenburg Gary B.
Kazaks Alexander
Korman Joshua
Chattopadhyay Urmi
Cooley & Godward LLP
Reconstructive Technologies, Inc.
Willse David H.
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