Implantable medical devices having microporous surface layers and method for reducing foreign body response to the same
Inventors
Marshall, Andrew J • Alvarez, Michel • Maginness, Max
Assignees
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Publication Number
US-8372423-B2
Publication Date
2013-02-12
Expiration Date
Abstract
This disclosure provides implantable devices coated with microporous surface layers with macrotopographic features that improve bio-integration at the interface of the implantable devices and the surrounding tissue.
Core Innovation
The microporous biomaterial provides a macrotopography defined by a plurality of peaks and valleys, where each peak is porous and has a specified peak height. At least two adjacent peaks define a valley, and the valley has a floor from which the heights of the adjacent peaks are measured. The surface of the floor of the valleys between the peaks is impermeable to fluids.
The microporous structure includes a plurality of pores forming a pore network in which substantially all pores are each interconnected to at least 2 other pores. Any two adjacent pores are connected by a throat, with a mean diameter of the pores and a mean throat diameter within stated micrometer ranges. This pore-and-throat geometry is incorporated into the macrotopographic peak-and-valley features.
An implantable device applies the microporous biomaterial as a microporous layer overlying a device body or as a textured surface layer comprising one or more granules of the microporous biomaterial. In the device constructions, the textured surface layer maintains the peak-and-valley macrotopography and the interconnected pore structure with specified mean pore and throat diameters, while preserving an impermeable valley-floor between peaks.
The disclosed tissue response approach associates the macrotopography and impermeable valley-floor with reduced foreign body response, including reduced fibrous avascular capsule thickness and reduced α-SMA myofibroblasts. The document further describes management of vascularization in the context of implantable microporous surfaces, and includes examples comparing macrotextured continuously microporous structures with intermittently nonporous valley-floor surfaces and comparing STARcuff to Dacron felt cuff and silver-ion VitaCuff.
Claims Coverage
The document provides three independent claims covering a microporous biomaterial, an implantable device with the microporous biomaterial layer, and an implantable device using granules forming a textured surface layer. Across these independent claims, the core inventive features are the macrotopographic peaks and valleys with an impermeable valley floor and the interconnected microporous pore network via throats with defined mean pore and throat diameters.
Interconnected micropores with throat connections and specified mean diameters
Substantially all pores are each interconnected to at least 2 other pores, where any two adjacent pores are connected by a throat, the mean diameter of the pores is between about 5 and about 100 micrometers, and the mean throat diameter of the throats is between about 5 micrometers and about 50 micrometers.
Macrotopography of porous peaks and valleys with impermeable valley floors
The macrotopography is defined by a plurality of peaks and valleys, where each peak is porous and has a height of between about 100 micrometers and about 2000 micrometers, and at least two adjacent peaks define a valley having a floor from which the heights of the adjacent peaks are measured, with the surface of the floor of the valleys between the peaks being impermeable to fluids.
Implantable device with microporous biomaterial overlying the device body
An implantable device includes a device body and a microporous biomaterial overlying the device body, where the microporous biomaterial has macrotopographic surface features and the plurality of interconnected pores connected by throats with the stated mean pore diameter and mean throat diameter, and the peak-and-valley macrotography includes porous peaks of the stated height range with an impermeable valley-floor.
Granule-based textured surface layer forming porous peaks and valleys
An implantable device includes a device body and a textured surface layer overlying the device body, where the textured surface layer comprises one or more granules of a microporous biomaterial; the granules form a surface macrotopography including peaks and valleys with peak height between about 100 micrometers and about 2000 micrometers, and each granule comprises a plurality of interconnecting pores with a mean pore diameter between about 5 and 100 micrometers connected by throats having a mean throat diameter between 5 and 50 micrometers, with the surface of the floor of the valleys between peaks being impermeable to fluids.
Across the independent claims, the patent centers on a microporous biomaterial or an implantable device surface that combines a specific peaks and valleys macrotopography with an impermeable valley floor and a microporous network where substantially all pores are interconnected via throats, with mean pore and mean throat diameters constrained to stated micrometer ranges.
Stated Advantages
Reduced foreign body response, including thinner or less dense fibrous avascular capsule and reduced α-SMA myofibroblasts.
Improved resistance to exit-site infection for STARcuff compared with Dacron felt cuff and silver-ion VitaCuff.
Promotes angiogenesis.
Documented Applications
Promoting angiogenesis by implanting an implantable device comprising the microporous biomaterial with the defined macrotopography and pore network.
Improving percutaneous exit-site sealing by using devices such as STARcuff, with comparative data against Dacron felt cuff and silver-ion VitaCuff for exit-site infection resistance.
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