Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis
Reexamination Certificate
2000-02-17
2002-04-23
Nguyen, Dave T. (Department: 1632)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
C623S016110, C623S018110, C623S066100, C128S898000, C433S223000, C433S226000
Reexamination Certificate
active
06376742
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the utilization of in situ polymers or copolymers to form a porous microcellular scaffold for the delivery, attachment, housing, protection, multiplication and growth of encapsulated cells. More particularly, the present invention relates to cells delivered using such a scaffold to augment,:repair or replace in vivo diseased, damaged or otherwise compromised tissues or organs of a living body.
BACKGROUND OF RELATED TECHNOLOGY
Organ dysfunction typically represents a serious complication in the living body. A treatment for such dysfunction involves organ transplantation, but the limited availability of suitable organs, compatibility problems with the host, and difficulties with subsequent healing presents serious obstacles.
Injury, illness or degeneration of a tissue function, its assembly or, ultimately, an organ, often present life threatening situations. Surgical interventions designed to correct this including graft transplantation and whole organ transplantation from a suitable donor. These techniques suffer from the limited availability of replacement organs, compatibility problems between the foreign organ and the host, as well as problems during the healing process which must be overcome to have a viable transplant. Currently, over 70,000 patients in the United States are waiting for donor organs of all sorts: With approximately 4,000 such organs available annually, many patients will never have a chance to become a recipient.
In vitro tissue engineering, where harvested cells populate a carefully prepared scaffold which is placed into a petri dish to generate an artificial organ, addresses some of these problems. Although a relatively new technology, in vitro tissue engineering has enjoyed some success. Trauma and healing problems associated with the implantation are some of the complications which have been experienced, however.
Surgical intervention into a living body necessarily is a traumatic event. The body responds, in most cases, with defense on both acute and chronic time scales. It is well recognized that the sequence of local events related to an implantation and subsequent healing may be represented as:
Injury→Acute Inflammation→Chronic Inflammation→Granulation Tissues→Foreign Body Reaction→Fibrosis.
A serious obstacle for tissue engineered implants is the general inability of the body to accept the implant, both acutely and chronically. The body typically “walls off” the foreign body (implant) with a fibrous capsule, interfering with or preventing the intended function of the implant. Often, inflammation and bacterial infection flood the implant site with byproducts, preventing the coexistence of the host and the implant. Although recent advances in host/implant interaction biology have resulted in greater understanding of the above events, an artificial organ which does not precipitate the above response has not yet been developed.
In vitro tissue engineering involves the collection of autologous cells collected from the tissue to be augmented. These cells are used to grow an implant resembling the organ to be repaired. Among the primary objectives of tissue engineering is the integration of the engineered tissue within the patient. This is accomplished by augmenting the cells through the implantation of a supporting device or prosthesis. The replacement of a diseased organ via a suitable transplant developed through such tissue engineering presents a potentially permanent solution for curing diseased tissue.
A number of compositions and approaches are known for such purposes as preparing prosthetic implants and repairing damaged tissues and organs. Engineered tissues have been manufactured which provide new opportunities for clinical treatment. While surgical approaches involving tissue augmentation, transplantation or total replacement have proven very successful, the invasive and open nature of these procedures, the potential for infection-related complications, and the long post-procedure rehabilitation and associated costs are all inherent concerns with these procedures. The ability of implants and hosts to co-exist, as well as the trauma, inflammation healing or rejection which immediately follows implantation are all critical considerations in tissue engineering. Such concerns contribute to high health care costs in the face of patient's needs for effective and less painful treatments.
There are several critical stages to the application of tissue engineered products. First, a suitable scaffold must be generated. Cells from a potential host or donor must then be harvested and introduced to the scaffold. Cells must then propagate to populate the scaffold and the scaffold and cell assembly must be implanted to the host body to become a functioning part thereof. The implant will initially attach to and communicate with the host through a mono-cellular layer only. Traumas and subsequent healing associated with the implantation complicates the subsequent process of acceptance.
Thus, there is a need for an approach to tissue engineering which is based on minimally invasive surgical procedures. Such an approach must provide a scaffold for cellular delivery such that the cells may multiply and grow, thereby augmenting or replacing the diseased tissue which will allow the implant tissue to grow within its “natural” surroundings. The present invention, involving in vivo tissue engineering which is targeted to both soft and hard tissue repair, is directed towards meeting these and other needs.
DETAILED DESCRIPTION
In one aspect of the invention there is provided a method of in vivo tissue engineering.
In another aspect of the invention there is provided a method for the in vivo formation of a microcellular scaffold for the attachment, housing and growth of autologous, allogenous or xenogenous cells encapsulated therein.
In another aspect of the invention there is provided a method of forming such a scaffold for the in vivo augmentation repair or replacement of diseased, damaged or otherwise compromised tissues of a living body.
In still a further aspect of the present invention there is provided an implantable bioartificial tissue structure which includes a multi-phased system useful as a cell support and a cellular mass within said multi-phase system.
In the efficient attainment of its various aspects, the present invention provides a method of in vivo tissue engineering which mediates tissue healing and regeneration processes by providing, in vivo, a porous, microcellular scaffold. The scaffold is populated by propagating cells from surrounding tissue or by encapsulated harvested cells delivered to the scaffold. A minimally traumatic athroscopic surgical procedure, in combination with Bio-RIM delivery, are utilized for introduction of this system to a site to be repaired in the body.
The scaffold is populated by cells either in spontaneous or cellular augmentation. In spontaneous augmentation, the surrounding cells will spread and populate to inhabit the scaffold. In cellular augmentation, encapsulated cells are delivered to this scaffold. An athroscopic procedure is used to deliver this unique polymer/encapsulated cells delivery system to a site to be repaired. The scaffold forming polymers are desirably biodegradable.
Biodegradable polyurethanes are desirably used in this scaffold system. The polyurethanes used are selected as a result of their structural properties, the ease of their preparation, and their biocompatability. This present invention includes an in situ polymerized microcellular scaffold which is formed while the encapsulated or otherwise protected cells are being seeded therein. Once the scaffold is generated, it desirably retains its shape and internal architecture to optimize its effectiveness to perform its cell housing function. Cells from the potential host or donor are then harvested and introduced to the scaffold, where they are permitted to propagate and populate the scaffold. The scaffold and cells assembly are either fully or partially
Zdrahala Ivanka J.
Zdrahala Richard J.
Hoffman & Baron LLP
Nguyen Dave T.
Nguyen Quang
LandOfFree
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