Chemistry: molecular biology and microbiology – Animal cell – per se ; composition thereof; process of... – Primate cell – per se
Reexamination Certificate
2000-10-03
2002-08-13
Ketter, James (Department: 1632)
Chemistry: molecular biology and microbiology
Animal cell, per se ; composition thereof; process of...
Primate cell, per se
C435S325000, C435S363000, C435S366000, C424S422000, C424S426000, C424S435000
Reexamination Certificate
active
06432710
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns the regeneration of tissues in a subject that have degenerated as a result of a disease or disorder in the subject. More particularly, the present invention concerns novel compositions for use in surgical and nonsurgical techniques that promote regeneration of tissue whose mass has been diminished due to a disease or disorder in a subject, correct defects in the skin of subjects, or augment tissue in subjects. Also disclosed is the use of a novel composition in conjunction with a biodegradable acellular matrix for ameliorating defects in the tissues, and methods .or using the novel composition.
BACKGROUND OF THE INVENTION
“Periodontal disease” is the term commonly used to describe inflammatory disease of the periodontium, i.e., the tissue surrounding and securing teeth to the jawbone. The condition is characterized by Inflammatory and degenerative processes that develop at the gingival margin (gingivitis) and lead to a progressive breakdown and resorption of the periodontal ligament and bone (periodontitis), oftentimes resulting in severe diminution of the periodontium. Periodontal disease is the leading cause of tooth loss in adults after middle age. [Anderson's Pathology, p. 2000, John M. Kissane ed., 9th ed. (1992)].
Periodontal disease results from the accumulation of bacterial plaque in the cap between the gingiva and the tooth. While anaerobic bacteria are the primary etiologic agents, the destructive process is believed to be mediated in large part by immunolocic reactions of the host. As the disease progresses, a periodontal pocket is established below the gingival margin, thus prolonging and promoting the inflammatory process. Successive inflammatory reactions result in the progressive erosion of the tooth-supporting tissues, i.e., the collagenous fibers making up the periodontal ligament and the bone pocket in which the tooth sits. [Reviewed in Anderson's Pathology, pp. 1999-2000, John M. Kissane ed., 9th ed. (1992); Shafer et al., A Textbook of Oral Pathology, 4th ed. (1983)].
Periodontal disease can be diagnosed by checking the gingiva for inflammation, probing the depths of periodontal pockets, checking clinical attachment level, and assessing bone loss by means of autoradiography. [Jeffcoat, M. K., et al., J. Am. Dent. Assoc., 128:713-724 (1997)].
A number of technIques, both surgical and nonsurgical, have been developed to treat periodontal disease. Particularly with respect to severe periodontitis, none of the currently available treatments are wholly satisfactory.
For relatively mild cases of periodontitis, practitioners have traditionally employed nonsurgical mechanical debridement (i.e. scaling and root planing) to remove the bacterial plaque whose accumulation perpetuates the disease, thereby reducIng inflammation. Mechanical debridement can be accomplished using manual, sonic or ultrasonic instruments. Scaling and root planing have been shown to decrease gingival inflammation, decrease probe depth, and promote maintenance of clinical attachment level. However, without resorting to surgical procedures, access to root surfaces and bony defects is restricted, and only limited debridement is possible. [Jeffcoat, M. K., et al., J. Am. Dent. Assoc. 128:713-724 (1997)].
As a result, nonsurgical scaling and root planing is insufficient to treat more severe cases of periodontitis, and it is necessary to resort to more aggressive surgical techniques. Surgical techniques comprise reflecting the gingival tissues to provide access to root surfaces and bone defects, in order that mechanical debridement may be accomplished directly. Following debridement, the gingival tissue is sutured back in position. Currently available surgical approaches entail substantial patient discomfort and fail to consistently provide satisfactory outcome.
There are a number of non-surgical, non-mechanical approaches to treating periodontal disease, including supragingival and subgingival irrigation and the application of chemical and antimicrobial agents. Yet none of these approaches have achieved more than marginal success [Jeffcoat, M. K., et al., J. Am. Dent. Assoc., 128:713-724 (1997)]. In particular, there are a number of deleterious side effects associated with the use of antibiotics, along with risks such as drug sensitivity and the emergence of antibiotic-resistant pathogens.
Another approach to combating destruction of the periodontal tissue has focused on inhibiting the matrix metalloproteases responsible for this destruction. Tetracyclines in particular have shown promise as inhibitors of extracellular collagenases, but cause the same side effects associated wash antibIotics in general. Modified forms of tetracycline have been developed which are non-antimicrobial and retain their ability to inhibit collagenases, but these chemically modified tetracyclines are not commercially available. [Ciancio, G. C. et al., J. Am. Dent. Assoc. 123:34-43 (1992)].
Because cell proliferation, cell migration and matrix synthesis are prerequisites for periodontal regeneration, some researchers have attempted to use tissue growth factors, for example insulin-like growth factor, platelet-derived growth factor, and transforming growth factor to promote periodontal regeneration.
In summary, none of the nonmechanical approaches to treating periodontitis have been able to offer more than modest, short term enhancement of traditional mechanical debridement. As noted in a 1997 review of techniques used in treating periodontal dIsease, “scaling and root planning accompanied by oral hygiene procedures remains the first mode of treatment for adult periodontitis.” [Jeffcoat, M. K. et al., J. Am. Dent. Assoc., 128:713-724 (1997)].
A great deal of research has been directed to methods of regenerating periodontal tIssue lost as a consequence of periodontal disease, but as yet no wholly satisfactory method is available. For the most part, efforts have focused on surgical approaches that fill the defects with a variety of materials (bone graftIng) or use guided tissue regeneration.
Bone grafting techniques involve the use of natural bone or synthetic bone materials. Natural bone grafts are typically either autografts (grafts transferred from one position in the body or a patient to another position in the body of the same patient) or allografts (grafts transferred from one person to another). Clinicians using natural bone grafts have had limited success in inducing new bone growth. Problems associated with the use of autografts include the need for a second surgical site and, in some cases, fresh grafts may be associated with root resorption. [Jeffcoat, M. K. et al., J. Am. Dent. Assoc. 128:713-724 (1997)].
Freeze-dried, demineralized bone has been used as an allografts and shown to promote bone formation. However, the predictability and the amount of bone fill achieved varies. [Jeffcoat, M. K. et al., J. Am. Dent. Assoc., 128:713-724 (1997)]. Since allografts are transferred from one person to another, the potential exists that viruses or other pathogens might be transferred to the patient.
Synthetic bone materials which have been investigated include plaster, calcium carbonates, and ceramics such as hydroxyapatite. Clinical trials have demonstrated that the use of synthetic grafts has resulted in improvements in probing depth and attachment level. Histologic findings, however, indicate that, in general, synthetic grafts act primarily as space fillers, with little if any regeneration. [Jeffcoat, M. K. et al., J. Am. Dent. Assoc., 128:713-724 (1997)].
Guided tissue regeneration is a surgical approach based on placing a membrane barrier under a soft tissue flap above the area of bone loss to enhance wound healing potential. [Ciancio, G. C. et al., J. Am. Dent. Assoc., 123:34-43 (1992)]. Investigators have studied both resorbable and nonresorbable membranes. A significant disadvantage of using a nonresorbable membrane is the requirement of a seco
Boss, Jr. William K.
Marko Olga
Fish & Richardson P.C.
Isolagen Technologies, Inc.
Ketter James
Li Janice
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