Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Light application
Reexamination Certificate
2002-09-25
2004-02-03
Gibson, Roy D. (Department: 3739)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Light application
C607S088000, C607S100000
Reexamination Certificate
active
06685730
ABSTRACT:
BACKGROUND OF THE INVENTION
Laser tissue welding refers to techniques by which tissues may be joined in response to exposure to light and the subsequent generation of heat. The goal of these techniques is the rapid joining of tissues with high tensile strength across the union, union throughout the depth of the targeted tissue, a minimum of scar tissue formation, and minimal damage to surrounding tissue. These techniques may also be beneficial in a number of minimally invasive surgical techniques. Laser tissue repair is under investigation or in use in many surgical disciplines for procedures such as closure of skin wounds, vascular anastamosis, occular repair, nerve repair, cartilage repair, and liver repair. Currently, laser tissue repair is accomplished either through welding, apposing two tissue surfaces then exposing to laser radiation to heat the tissues sufficiently to join them, or through soldering, wherein an exogenous material such as a protein or synthetic polymer is placed between two tissue surfaces to enhance joining of the tissues upon exposure to laser radiation. Temperatures greater than 50° C. can induce tissue union. This is believed to be induced by the denaturation of proteins and the subsequent entanglement of adjacent protein chains.
In traditional approaches, tissue welding is accomplished when laser light is absorbed by tissue components such as water or hemoglobin, producing sufficient heat to cause denaturation of collagens and other proteins with subsequent entanglement of adjacent protein chains (Guthrie, 1991). The laser light used in this traditional approach does not discriminate between the wound surface and other tissue. As a result, the success of laser tissue welding has been limited because of (1) the generation of superficial welds with poor mechanical integrity as a result of poor optical penetration and (2) excessive damage to adjacent tissues (Bass, et al. 1995; DeCoste, et al., 1992; Robinson, et al., 1987).
Given these limitations, focus has turned to the investigation of exogenous materials to facilitate the transfer of heat to enable wound closure. The exogenous materials used to facilitate laser tissue welding fall into two categories: those selected to preferentially convert light to heat and those selected to facilitate wound closure and healing. Light absorbing materials currently employee include indocyanine green (U.S. Pat. No. 6,221,068, Bass, et al., 1992; Cooper, et al., 2001; and McNally, et al., 1999), India ink (Fried, et al., 2000), and carbon black (Lauto, et al., 2001). Other examples of the use of chromophores, either alone or in combination with other components, include the works of Birch, Cooper, McNally, Sorg and others. The second class of compounds, commonly referred to as solders, has the primary task of facilitating tissue bonding and healing, and is principally used in conjunction with light-absorbing materials as described above. Ranging from viscous solutions to semi-solid pastes, solders are typically made from biocompatible materials like albumin (Wider, et al., 2001; McNally, et al., 2000; Menovsky, et al., 2001; Lauto, et al., 2001; Zuger, et al., 2001; Bleustein, et al., 2000; Poppas, et al., 1993), albumin with hyaluronic acid (Kirsch, et al., 1997; Ott, et al., 2002), fibrinogen (Wider, et al., 1991), collagen (Small, et al., 1997), cellulose (Bleustein, et al., 2000) or chitosan (Lauto, et al., 2001). From these studies it can be ascertained that the primary duties of a solder are to keep dyes immobile when applied in vivo and to provide a sealant across uneven wound edges.
The use of the nanoparticles of the present invention over chemical chromophores is desirable due to the ability to achieve stronger optical absorption and heat generation, the opportunity for tunable absorption, potentially better biocompatibility, and the ability to better target binding to specific cells or tissues.
In many applications, it is desirable to target cells and tissue for localized heating. The therapeutic effects range from the destruction of cancerous cells and tumors, to the therapeutic or cosmetic removal of benign tumors and other tissue. Techniques which effect precise localized heating and illumination would allow one to enjoy therapeutic and diagnostic benefits, while minimizing the collateral damage to nearby cells and tissue. It is desirable that such techniques be amenable to both in vitro and in vivo therapeutic and diagnostic applications of induced hyperthermia and imaging, respectively, of cells and tissue.
A potentially useful in vivo application of such a technique has been recognized for cancer treatment. For example, metastatic prostate cancer is a leading cause of mortality in American men. Estimates indicate that greater than one in every eleven men in the U.S. will develop prostate cancer. Accurate determination of the extent of local disease is often difficult. Methods for accurately detecting localized prostate disease are greatly needed. In addition, localized prostate cancer is generally treated with either radical prostatectomy or radiation therapy. Both of these procedures are plagued by significant morbidity. Minimally invasive treatment strategies with low associated morbidity are made feasible through such applications and could potentially dramatically improve prostate cancer therapy.
A number of techniques have been investigated to direct therapeutic agents to tumors. These have included targeting of tumor cell surface molecules, targeting regions of activated endothelium, utilizing the dense and leaky vasculature associated with tumors, and taking advantage of the enhanced metabolic and proteolytic activities associated with tumors. Antibody labeling has been used extensively to achieve cell-selective targeting of therapeutic and diagnostic agents. A number of approaches have been taken for antibody-targeting of therapeutic agents. These have included direct conjugation of antibodies to drugs such as interferon-alpha (Ozzello, et al., 1998), tumor necrosis factor (Moro, et al., 1997), and saporin (Sforzini, et al., 1998). Antibody conjugation has also been used for tumor-targeting of radioisotopes for radioimmunotherapy and radioimmunodetection (Zhu, et al., 1998). Currently, there is a commercial product for detection of prostate cancer (ProstaScint) that is an antibody against prostate-specific membrane antigen conjugated to a scintigraphic target (Gregorakis, et al., 1998).
The nanoparticles that are the subject of this invention are amenable to these types of targeting methodologies. Examples of such have been described previously in the following copending patent applications: U.S. application Ser. Nos. 09/779,677 and 09/038,377, and international application PCT/US00/19268, which are fully incorporated by reference as if expressly disclosed herein. The nanoparticle surfaces can easily be modified with antibodies, peptides, or other cell-specific moieties. The utility of these nanoparticles in the localized treatment of disease is a consequence of their photothermal properties. It has been shown that elevated temperatures are useful in joining tissue. (Lobel, et al., 2000; Fried, et al., 1999). Judicious placement of the nanoparticles to the area to be treated, followed by the proper excitation results in a localized heating which forms the basis of the various nanoparticle treatment strategies demonstrated to date.
We now demonstrate that nanoparticles that strongly absorb light corresponding to the output of a laser are useful for another therapeutic application, namely as enhancing agents for laser tissue welding procedures. Specifically, gold-silica nanoshells are designed to strongly absorb light at 820 nm, matching the output of the diode laser used in these experiments. The nanoshells are coated onto the surfaces of two pieces of tissue at the site where joining was desired. Upon exposure to the diode laser, the tissue surfaces are joined when they had first been treated with nanoshells but are not joined under these illumination conditions without nanoshell treatmen
Drezek Rebekah
Halas Nancy J.
Sershen Scott
West Jennifer L.
Fulbright & Jaworski L.L.P.
Gibson Roy D.
Rice University
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