Chemistry: analytical and immunological testing – Peptide – protein or amino acid
Reexamination Certificate
1999-04-06
2001-11-27
Mulcahy, John (Department: 3739)
Chemistry: analytical and immunological testing
Peptide, protein or amino acid
C436S518000, C606S008000, C424S426000, C424S428000, C530S300000
Reexamination Certificate
active
06323037
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composition and a method for tissue welding.
BACKGROUND OF THE INVENTION
Traditional methods for closing tissue wounds or incisions include the use of sutures, clips, or staples. While such techniques are generally adequate in sealing tissue wounds or incisions, they have associated problems that limit their use. For example, the use of sutures, clips or staples in closing tissue wounds can often lead to scar formation, infection, and a multitude of immunological responses. Tissue incompatibility with sutures, clips, or staples may cause fistulas, granulomas, and neuromas that can be painful and difficult to treat. Sutures, clips, or staples may also tend to cut through weak parenchymatous or poorly vascularized tissue. Additionally, sutures leave behind a tract that can allow for leakage of fluids and can provide a convenient entry point for a variety of organisms.
The success of traditional methods in sealing tissue wounds or incisions also is very dependent on the skill of the practitioner performing such methods. The manual dexterity and eyesight of the practitioner impose severe limits on the use of sutures, staples, and clips, especially when microsurgery is being performed.
An alternative to traditional methods for sealing tissue wounds or incisions is the use of compositions suitable for tissue welding. By “tissue welding” it is meant that an energy source is used to excite the composition, which results in the sealing or closure of the tissue wound or incision. Typically, a tissue welding composition will be applied to the area of the tissue that requires sealing. Upon excitation by an energy source, the composition fuses to the tissue, and the bonding between the composition and the tissue allows the severed parts of the tissue to be proximal to each other, much in the same way as when sutures, staples, or clips are used. Such tissue welding compositions are absorbable within a few weeks and, therefore, do not cause tissue scar formation.
Despite the general advantages that tissue welding has over the more traditional methods, current compositions used in tissue welding suffer from numerous drawbacks. Compositions presently in use solubilize in physiological fluids after application and before excitation by an energy source. Blood dilution of the composition after application, but before excitation, alters the shape and rigidity of the composition as it existed when the composition was applied to the tissue. Such alterations to the shape and rigidity of the composition prior to excitation change the energy absorption characteristics of the composition and weaken its repair tensile strength. The result is an impairment of the reliability and reproducibility of the tissue welding technique.
In view of the foregoing problems, there exists a need for a tissue welding composition that is not soluble or has a low solubility in physiological fluids prior to excitation by an energy source. The present invention provides such a composition and a related method of use. These and other advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a physiological fluid-insoluble composition for tissue welding comprising an active compound, a physiologically compatible solvent and an energy converter. The present invention also provides a method for welding a tissue comprising (a) contacting tissue with a physiological fluid-insoluble composition comprising an active compound, a physiologically compatible solvent, and an energy converter, and (b) exciting the composition such that the tissue becomes welded.
The invention may best be understood with reference to the following detailed description of the preferred embodiments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a composition for tissue welding and a method for welding a tissue. The present inventive composition comprises an active compound, a physiologically compatible solvent, and an energy converter, wherein the active compound is present in the composition in such a concentration that the composition is insoluble in physiological fluids. The present invention also provides a method for welding a tissue comprising (a) contacting tissue with a composition comprising an active compound, a physiologically compatible solvent, and an energy converter, wherein the active compound is present in the composition in such a concentration that the composition is insoluble in physiological fluids, and (b) exciting the composition such that the tissue becomes welded.
By the term “insoluble,” it is meant that the composition is insoluble or has a low solubility in water or in other physiological fluids. A composition that is insoluble or has a low solubility will substantially retain its structural properties (i.e., its shape and rigidity) in water or in other physiological fluids, preferably, at a temperature of about 20° C. to about 50° C. for at least about 5 minutes, more preferably, at a temperature of about 25° C. to about 45° C. for at least about 5 minutes, and, most preferably, at a temperature of about 25° C. to about 40° C. for at least about 5 minutes.
The active compound can be any suitable, safe and efficacious organic substance that imparts to the composition the desired degree of insolubility and that allows the composition to bond or fuse to animal tissue, e.g., human tissue. Furthermore, the active compound can be any combination of any suitable organic substances. Preferably, the active compound is a protein or peptide; more preferably, the active compound is selected from the group consisting of albumin, collagen, myoglobin and fibrinogen; and most preferably, the active compound is albumin.
The concentration of the active compound is such that the composition will have the desired degree of insolubility. Thus, the active compound concentration will vary as a function of the type of active compound and the type and concentration of solvent of which the composition is composed. When the active compound is albumin, the active compound concentration is, preferably, equal to or greater than about 70% (w/w), more preferably, than about 75% (w/w), in a physiologically compatible solvent.
In order to achieve high concentrations of active compound in the composition, any suitable physical, chemical or mechanical process can be utilized, particularly, mechanical compression, thermal treatment, irradiation, various chemical treatments, combinations thereof, and the like. Whatever means of combining the active compound and solvent are chosen, the resulting combination is, preferably, homogeneous.
While any suitable solvent can be used in the context of the present invention, the solvent is such that the composition has the desired degree of insolubility in physiological fluids. Preferably, the solvent is such that it sufficiently solvates the active compound without completely dissolving the active compound. More preferably, the solvent is water (e.g., H
2
O or D
2
O) because water can function both as a solvent with respect to albumin and as an energy converter. The choice of solvent depends on the concentration of the solvent and the type and concentration of the active compound utilized.
The concentration of the solvent is such that the composition will have the desired degree of insolubility in physiological fluids and will vary as a function of the type of solvent and the type and concentration of the active compound of which the composition is comprised. Preferably, the concentration of the solvent is such that the active compound is not completely dissolved. When the active compound is albumin, the sum of the concentrations of the solvent and the energy converter is preferably less than about 25% (w/w). In most cases, the concentration of the solvent will be greater than the sum of the concentrations of the energy converter, when the energy converter is different from the solv
Lauto Antonio
Poppas Dix P.
Cornell Research Foundation Inc.
Farah Ahmed
Leydig , Voit & Mayer, Ltd.
Mulcahy John
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