Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-10-23
2004-09-28
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S154000, C604S131000
Reexamination Certificate
active
06796957
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to medical systems and procedures and more particularly to devices and methods of their use for injection of a therapeutic agent into the surface of an interior body cavity of a living being.
2. Background Information
Market expansion in cardiovascular and cardiothoracic surgery in past years has largely been driven by increases in open-heart surgical bypass procedures, but new opportunities for growth will come from products associated with least-invasive procedures. The positive outcomes seen thus far with these techniques, accompanied by continued physician acceptance, will lead to a gradual erosion of the market for traditional open-heart surgery.
Driven by capitation and cost-cutting measures associated with managed care, these evolving techniques and procedures not only hold the promise of reduced trauma to patients, but also reduce the significant costs associated with traditional open-heart surgery. Markets for least-invasive invasive approaches to cardiothoracic surgery, including equipment and disposables, are predicted to grow at tremendous rates for the next twenty years.
Within the past few years, an increasing number of centers worldwide have begun performing revolutionary techniques, such as beating-heart coronary artery bypass and laser transmyocardial revascularization (TMR). These developing procedures offer the potential of expanding the size of the eligible patient base by providing significantly reduced patient trauma and lower costs, as well as providing a viable alternative to patients unable to undergo open heart surgery.
Bone marrow cells and liquid aspirate are believed to be the source of angiogenic peptides known as growth factors. In addition, recent studies have shown that bone marrow cells include stem cells that differentiate into angioblasts. Angiogenesis represents the postnatal formation of new blood vessels by sprouting from existing capillaries or venules. During angiogenesis, endothelial cells are activated from a quiescent microvasculature (turnover of thousands of days) to undergo rapid proliferation (turnover of a few days).
In one technique currently in clinical stage testing, autologous bone marrow cells are transplanted into the heart to restore heart function. In one such procedure, autologous bone marrow cells obtained by aspiration from the patient's hipbone are transplanted into transventricular scar tissue for differentiation into cardiomyocytes to restore myocardial function (S. Tomita, et al.,
Circulation
100:19 Suppl II 247-56, 1999). In another technique, autologous bone marrow cells are harvested and transplanted into an ischemic limb or ischemic cardiac tissue as a source of angiogenic growth factors, such as VEGF (A. Sasame, et al.,
Jpn Heart J
, Mar 40:2 165-78, 1999).
To perform such techniques, various types of needles and needle assemblies used for bone marrow biopsy, aspiration, and transplant have been proposed and are currently being used. Many such bone marrow harvesting devices include a cannula, stylet with cutting tip, or trocar that can be used to cut a bone marrow core sample. On the other hand, devices designed for withdrawal of liquid bone marrow aspirate typically comprise a large gauge hollow needle attached to a device for creating a negative pressure to aspirate the liquid bone marrow.
Current procedures used for harvesting, purification and reinjection of autologous bone marrow cells may require sedation of the patient for a period of three to four hours while the bone marrow aspirate is prepared for reinjection. In addition, the present procedure involves great risk of infection for the subject because the harvested bone marrow material is routinely aspirated in an operating or recovery room and then transferred after aspiration to a laboratory where the aspirate is placed into a centrifuge for gravity separation of bone marrow cells from the aspirate. In many cases the bone marrow aspirate is transferred into a specially designed centrifuge tube for the gravity separation. The separated bone marrow cells are then removed from the centrifuge tube into a syringe and transferred back to the recovery room or operating room for reinjection into the patient. Thus, the bone marrow aspirate is handled under potentially non-sterile conditions and reinjected into the patient as a potentially non-sterile preparation.
Generally, the processed cells are injected by catheter into the ischemic site where reperfusion is required. For example, it is known to deliver bone marrow cells by pericardial catheter into the subject's myocardium to stimulate angiogenesis as a means of reperfusing ischemic tissue with collaterally developed capillaries. However, prior art methods for preparation and injection of non-sterile bone marrow aspirate risk introduction of pathogens with consequent increased risk of infection for the patient.
Angiogenic peptides like VEGF (vascular endothelial growth factor) and bFGF (basic fibroblast growth factor) have also entered clinical trials for treatment of coronary artery disease. Attempts are being made to devise clinically relevant means of delivery and to effect site-specific delivery of these peptides to ischemic tissue, such as heart muscle, in order to limit systemic side effects. Typically cDNA encoding the therapeutic peptide is either directly injected into the myocardium or introduced for delivery into a replication-deficient adenovirus carrying the cDNA to effect development of collateral arteries in a subject suffering progressive coronary occlusion.
Recently, various publications have postulated on the uses of gene transfer for the treatment or prevention of disease, including heart disease. See, for example, Mazur et al., “Coronary Restenosis and Gene Therapy,” Molecular and Cellular Pharmacology, 21:104-111, 1994; French, “Gene Transfer and Cardiovascular Disorders,” Herz 18:222-229, 1993; Williams, “Prospects for Gene Therapy of Ischemic Heart Disease,” American Journal of Medical Sciences 306:129-136, 1993; Schneider and French, “The Advent of Adenovirus: Gene Therapy for Cardiovascular Disease,” Circulation 88:1937-1942, 1993. Another publication, Leiden et al, International Patent Application Number PCT/US93/11133, entitled “Adenovirus-Mediated Gene Transfer to Cardiac and Vascular Smooth Muscle,” reports on the use of adenovirus-mediated gene transfer for the purpose of regulating function in cardiac vascular smooth muscle cells. Leiden et al. states that a recombinant adenovirus comprising a DNA sequence that encodes a gene product can be delivered to a cardiac or vascular smooth muscle cell and the cell maintained until that gene product is expressed. According to Leiden et al., muscle cell function is regulated by altering the transcription of genes and changes in the production of a gene transcription product, such as a polynucleotide or polypeptide. Leiden et al. describe a gene transfer method comprising obtaining an adenoviral construct containing a gene product by co-transfecting a gene product-inserted replication deficient adenovirus type 5 (with the CMV promoter) into 293 cells together with a plasmid carrying a complete adenovirus genome, such as plasmid JM17; propagating the resulting adenoviral construct in 293 cells; and delivering the adenoviral construct to cardiac muscle or vascular smooth muscle cells by directly injecting the vector into the cells.
There are impediments to successful gene transfer to the heart using adenovirus vectors. For example, the insertion of a transgene into a rapidly dividing cell population will result in substantially reduced duration of transgene expression. Examples of such cells include endothelial cells, which make up the inner layer of all blood vessels, and fibroblasts, which are dispersed throughout the heart. Targeting the transgene so that only the desired cells will receive and express the transgene, and the transgene will not be systemically distributed, are also critically important considerations. If this i
Carpenter Kenneth W.
Fourmont Michelle
Li Hong
Malphus E. Thomas
Sasamine Kazuo
Gray Cary Ware & Freidenrich LLP
Mendez Manuel
Myocardial Therapeutics, Inc.
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