Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
2000-07-25
2001-12-04
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C424S423000, C424S422000, C604S890100, C604S891100, C623S005110
Reexamination Certificate
active
06326019
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to amniotic membrane grafts especially usable in the repair of injured eyes. This invention also encompasses: a method for separating and preserving amniotic membrane for a graft; the graft that is created by such method; and methods of repairing eyes and other organs while using these grafts.
2. The Prior Art
Terminology:
An amniotic membrane has two major components: the basement membrane and stroma. The side of the amniotic membrane dominated by the basement membrane is referred to as the “basement membrane side”. The side of the amniotic membrane dominated by the stroma is referred to as the “stroma side”. An autograft is a tissue transplant from the same recipient. When used in subcutaneous tunnels, autografts of the amnion become a permanent structure. In contrast, allografts are replaced by hyaline-like material.
An allograft is a tissue transplant to a recipient from a donor of another individual of the same species.
Previous Clinical Applications:
The fetal membrane including amnion (amniotic membrane) and chorion has been used in surgeries documented as early as 1910 and has been reviewed by Trelford and Trelford-Sauder in 1979. See Trelford and Trelford-Sauder,
The Amnion in Surgery, Past and Present
, 134 A
M
J. O
BSTET
. G
YNECOL
833 (1979). In the beginning, the fetal membrane was used by Davis in 1910 on burned and ulcerated skins with additional coverage of warm paraffin and dressing. In 1940, De Rötth used fetal membrane for ophthalmic reconstruction of symblepharon, and noted a success in one out of six cases. See De Rötth,
Plastic Repair of Conjunctival Defects with Fetal Membranes
, 23 A
RCHIVES OF
O
PTHAMOLOGY
522 (1940). In 1952, Douglas thought chorion might be more useful for skin use. Massee and colleagues in 1962 used the fetal membrane in dogs to treat pelvic basins after total exenteration; however, the human trials proved disappointing.
The isolated amnion alone was first used by Brindeau in 1935 and Burger in 1937 as a graft in forming artificial vaginas. Between 1941 and 1948, Kubanyi used “live” amnion in patients with burns, traumatic skin wounds, and enterocutaneous fistula secondary to surgery for lysis of adhesions. The isolated amnion, with preservation in a technique termed “amnioplastin”, was first reported by Chao and associates in 1940. Chao used amnioplastin for continual dural repair, peripheral nerve injuries, conjunctival graft and flexor and tendon repair. In the Russian literature, this technique was also used for fresh trauma by Pikin in 1942.
Although all reports were enthusiastic, mention of “amnioplastin” disappeared from the literature with no real explanation. No critical reports regarding isolated, non-living amnion with preservation were found for a thirty-year period. Furthermore, if there were failures of treatment during this time, they were not reported. This gap in research ended in 1972 with the research of Trelford and associates, cited above. Trelford, using isolated amnion with an early form of preparation, showed that the orientation with stromal side down provided more consistent “take.” Robson and colleagues noted in 1972 that, when used in partial-thickness skin wounds, no “take” occurs, and the amnion peels off. In 1973 and later, Trelford and associates reported its use as a dressing on full-thickness skin wounds, to replace pelvic peritoneum, and to cover exposed deep surfaces in pedicle graft procedures, to treat non healing skin wounds in diabetic patients, as a graft over the surgical defect of total glossectomy, as a biological dressing in omphalocele, and in the prevention of meningocerebral adhesions following head injury.
Previous Methods of Preparation and Preservation:
All of the above-mentioned applications appeared to have used live tissues or tissue removed and preserved “lively” in a special solution before use. For example, de Rötth put the fetal membrane, amnion and chorion together without separation, in “tepid Locke solution”, and one to fifteen hours after cesarean section the tissue was implanted to patients. Reports which appeared after 1980 refer to live amniotic membranes having been used (See 34 J. R
EPRODUCTIVE
M
ED
. 198 (1989) and 27 J. P
EDIATRIC
S
URGERY
882 (1992)). For “amnioplastin”, Chao and associates isolated the amnion, placed it in 70% alcohol, and then dried it in an oven prior to use. Robson and associates rinsed the membrane in a 0.025% NaOH solution and showed that it remained sterile up to six weeks when stored in saline containing penicillin at 4° C. Trelford and associates found that amniotic membranes stored at 4° C. in 0.5N saline to which polymyxin, ampicillin, gentamicin, and amphotericin B was added were sterile at the end of four hours and remained so for at least 48 hours.
SUMMARY OF THE INVENTION
Human amniotic membrane, obtained and preserved in a new way is made into a graft which is effective in: promoting healing of persistent corneal epithelial defects with ulceration; reduction of inflamation, angiogenesis and scarring; restoration of the epithelal phenotype; numerous further uses in ocular surface reconstruction; and as a substrate alternative to conjunctival autograft during the “bare sclera” removal of pterygia. In addition, when combined with limbal allografts, amniotic membrane transplantation is useful for ocular surface reconstruction in patients with advanced ocular cicatricial pemphigoid, Stevens-Johnson syndrome, chemical and thermal burns, aniridia, atopic keratitis and idiopathic limbal stem cell deficiency. After the placenta is obtained and cleaned, the amnion is separated from the chorion by blunt dissection, flattened onto filter paper with the epithelium surface facing away from the paper, and cut into small sheets.
These sheets are stored in a media composed, for example, in Dulbecco's Modified Eagle Medium and glycerol at the ratio of 1:1 (v/v), and frozen at −80° C. until just prior to use as a graft. When thawed to room temperature the day of use, the cells of the graft membrane have been killed, probably by ice crystals from the surrounding storage medium. The side of the membrane adherent to the filter paper is opposed to the surgical site.
OBJECTS OF THE INVENTION
It is an object of this invention to prepare grafts made from amniotic membrane.
It is another object of this invention to prepare grafts made from amniotic membrane that can be stored for long periods of time.
It is another object to this invention to prepare grafts that have been treated so that the grafts contain agents that can be delivered to the recipient when attached to the recipient.
It is another object of this invention to provide an improved substrate alternative to conjunctival autograft during the “bare sclera” removal of pterygia.
It is another object of the invention to provide an improved substrate alternative to conjunctival flaps to promote healing of corneal epithelial defects with ulceration.
It is another object of this invention to provide an improved method for conjunctival surface reconstruction for symbelpharon lysis.
It is another object of this invention to provide an improved method for surgical removal of tumors, lesions, or scar tissue from the conjunctival or corneal surface.
It is another object of this invention to reduce the corneal haze induced by excimer laser photerefractive/therapeutic keratectomy.
It is another object of this invention to promote successful glaucoma surgeries by correcting bleb leakage.
It is another object of this invention to prevent recurrence of band keratopathy.
Other objects of the invention and advantages over the prior art, as well as differences from the prior art, will become fully appreciated from the following discussion of: Embryogenesis and Histology; Components; Applications in Basic Research; and the Description of the Preferred Embodiments, along with description of numerous proposed uses of the resulting, improved graft.
Embryogenesis and Histology:
Early in the process of blastocyst implantation, a sp
Di Nola-Baron Liliana
Hamilton Brook Smith & Reynolds P.C.
Page Thurman K.
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