Tissue inplant systems and methods for sustaining viable high cell densities within a host
First Claim
1. An assembly for embedding in host tissue, where it is exposed to physiological stresses and vascularization by host tissue comprisingwall means defining a chamber for holding cells while embedded in host tissue, the wall means including means for forming a porous boundary between host tissue and the cells in the chamber, the porous boundary being characterized bya tensile strength and a pore size sufficient to isolate the implanted cells from an immune response of host tissue in which the chamber is embedded;
- anda metabolic transit value including a permeability value of greater than about 1.5×
10-4 cm/sec. for 125 I-labeled insulin as determined by pseudo-steady state diffusion in a diaphragm cell,whereby the wall means sustains a flux of nutrients from host tissue in which the chamber is embedded to the cells in the chamber and waste products from the cells in the chamber to host tissue in which the chamber is embedded in the absence of close vascular structures to thereby sustain viability of the cells in the chamber until vascular structures of host tissue form close to the porous boundary.
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Accused Products
Abstract
Implant assemblies and methodologies provide immuno-protection for implanted allografts, xenografts, and isografts. The assemblies and methodologies establish a boundary between the host and the implanted cells. The boundary has a pore size, an ultimate strength, and a metabolic transit value that assures the survival of the cells during the critical ischemic period and afterward. The boundary allows the fabrication and clinical use of implant assemblies and methodologies that can carry enough cells to be of therapeutic value to the host, yet occupy a relatively small, compact area within the host.
730 Citations
11 Claims
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1. An assembly for embedding in host tissue, where it is exposed to physiological stresses and vascularization by host tissue comprising
wall means defining a chamber for holding cells while embedded in host tissue, the wall means including means for forming a porous boundary between host tissue and the cells in the chamber, the porous boundary being characterized by a tensile strength and a pore size sufficient to isolate the implanted cells from an immune response of host tissue in which the chamber is embedded; - and
a metabolic transit value including a permeability value of greater than about 1.5×
10-4 cm/sec. for 125 I-labeled insulin as determined by pseudo-steady state diffusion in a diaphragm cell,whereby the wall means sustains a flux of nutrients from host tissue in which the chamber is embedded to the cells in the chamber and waste products from the cells in the chamber to host tissue in which the chamber is embedded in the absence of close vascular structures to thereby sustain viability of the cells in the chamber until vascular structures of host tissue form close to the porous boundary. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of implanting cells comprising the steps of
surrounding at least a portion of the implanted cells with a porous boundary that has a tensile strength and a pore size sufficient to isolate the implanted cells from an immune response of host tissue; - and a metabolic transit value including a permeability value of greater than about 1.5×
10-4 cm/sec. for 125 I-labeled insulin as determined by pseudo-steady state diffusion in a diaphragm cell, andembedding the porous boundary within host tissue whereby the porous boundary sustains a flux of nutrients from host tissue to the cells within the boundary and waste products from the cells within the boundary to host tissue in which the boundary is embedded sufficient to maintain viability of the cells within the boundary until vascular structures of host tissue form close to the boundary. - View Dependent Claims (10, 11)
- and a metabolic transit value including a permeability value of greater than about 1.5×
Specification