Biodegradable medical implants, polymer compositions and methods of use
Inventors
Imran, Mir • Patel, Sanjay • Harris, Joel
Assignees
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Publication Number
US-10046085-B2
Publication Date
2018-08-14
Expiration Date
Abstract
Embodiments of the invention provide compositions include bio degradable polymers, medical implants fabricated from these compositions and methods of using such implants. Many embodiments provide medical implants including a first polymer backbone having a first rate of biodegradation and a second polymer backbone having a second rate of biodegradation faster than the first rate. In some embodiments, the second backbone is configured to be replaced by a natural tissue layer. The first backbone provides a scaffold for the implant while the second backbone degrades. This scaffold can enhance mechanical properties of the implant including various aspects of mechanical strength such as tensile, bending, hoop and yield strength; and elasticity. The scaffold also serves to maintain a minimum level of structural support of the implant during the period of degradation of the second backbone or for the entire life of the implant so that the implant does not mechanically fail.
Core Innovation
The invention relates to a biodegradable medical implant for implantation in the human body that uses a polymer composition with two differently degradable backbones. A first polymer backbone comprises a polyurethane and has a first rate of biodegradation, while a second polymer backbone comprises polyglycolic acid (PGA) or polyglycolic lactic acid (PGLA) and has a second rate of biodegradation that is faster than the first rate. The two backbones are configured to provide differential biodegradation behavior during implantation.
The degradation rates are configured so that the first polymer backbone provides a scaffold for the implant that is maintained while the second polymer backbone degrades. In this way, the implant maintains structural function as the faster-degrading PGA/PGLA component decreases. The disclosures further discuss scaffold performance and implant stiffness, including weight ratio ranges of polyurethane to PGA or PGLA.
The polymer backbones are cross-linked, including configurations where the first and second polymer backbones are cross-linked. In particular, one disclosed cross-linking arrangement includes a urethane linkage between an isocyanate side group on the first polymer backbone and a methylene side group on the second polymer backbone. The disclosures further discuss scaffold and implant mechanical properties, including tensile strength and stiffness, and include optional polypeptides intended to promote cell adhesion and migration on surfaces of the implant.
Claims Coverage
The partial content includes two independent claims, each centered on a biodegradable medical implant with two polymer backbones having different biodegradation rates, and with cross-linking and weight-ratio constraints. The independent claims differ in the level of cross-linking specificity and in the cross-linking linkage recited in the later claim.
Differential biodegradation scaffold using polyurethane and PGA/PGLA
A biodegradable medical implant comprising a polymer composition mixture of a first polymer backbone comprising a polyurethane with a first rate of biodegradation and a second polymer backbone cross-linked to the first polymer backbone having a second rate of biodegradation faster than the first rate, wherein the second polymer comprises PGA or PGLA, and wherein the degradation rates are configured such that the first polymer backbone provides a scaffold that is maintained while the second polymer backbone degrades.
Cross-linked polyurethane scaffold with urethane linkage to PGA/PGLA at a defined weight ratio
A biodegradable medical implant comprising a polymer composition mixture of a first polymer backbone having a first rate of biodegradation comprising polyurethane and a second polymer backbone having a second rate of biodegradation faster than the first rate comprising PGA or PGLA, wherein the degradation rates are configured such that the first polymer backbone provides a scaffold for the implant maintained while the second polymer backbone degrades, wherein the first and second polymer backbones are cross-linked by a urethane linkage between an isocyanate side group on the first polymer backbone and a methylene side group on the second polymer backbone, and wherein a weight ratio of polyurethane to PGLA or PGA ranges from about 20:80 to 80:20.
Across both independent claims, the core claim coverage is directed to maintaining a polyurethane-based scaffold while a faster-degrading PGA/PGLA backbone degrades, using cross-linking between the backbones and defining polyurethane-to-PGA/PGLA weight ratio ranges. One independent claim additionally specifies urethane linkage between an isocyanate side group on the polyurethane and a methylene side group on the PGA/PGLA.
Stated Advantages
Provides a scaffold that is maintained while the second polymer backbone degrades.
Improves mechanical properties, including tensile strength and stiffness, as described through scaffold function.
Documented Applications
A vascular graft with an inner/tissue layer and an outer layer.
A mesh or membrane implant.
An intestinal graft including a central portion and side portions.
A stent, including a biliary stent, a vascular stent, or a coronary artery stent.
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