Differential healing and neovascularization of ePTFE implants in subcutaneous versus adipose tissue

Williams, Stuart K.; Berman, Scott S.; Kleinert, Leigh B.

doi:10.1002/(sici)1097-4636(19970615)35:4<473::aid-jbm7>3.0.co;2-e

Cited by 39 publications

(18 citation statements)

References 12 publications

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“…Similar to previously described observations12, 13, 23, bare ePTFE implants, regardless of whether or not the polymer was modified, were surrounded by a matrix-rich, cellular layer of tissue (Fig. 1).…”

Section: Resultssupporting

confidence: 89%

Encapsulation of ePTFE in prevascularized collagen leads to peri‐implant vascularization with reduced inflammation

Gruionu

Stone

Schwartz

et al. 2010

J Biomedical Materials Res

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During the typical healing response to an implanted biomaterial, vascular-rich granulation tissue forms around the implant and later resolves into a relatively avascular, fibrous capsule. We have previously shown that a microvascular construct (MVC) consisting of isolated microvessel fragments suspended in a collagen I gel forms a persistent microcirculation in lieu of avascular scar when implanted. The current study evaluated the potential for microvascular constructs to maintain a vascularized tissue environment around an implanted biomaterial. An analysis of the peri-implant tissue around bare expanded polytetrafluoroethylene (ePTFE), ePTFE embedded within a microvascular construct, or ePTFE embedded within collagen alone revealed that the presence of the MVC, but not collagen alone, promoted vascular densities comparable to that of the granulation tissue formed around bare ePTFE. The vessels within the microvascular construct surrounding the ePTFE were perfusion competent, as determined by India ink perfusion casting, and extended into the interstices of the polymer. In contrast to bare ePTFE, the presence of the MVC or collagen alone significantly reduced the number of activated macrophages in association with ePTFE. Similar results were observed for ePTFE modified to increase cellularity and prevent the formation of an avascular scar. The microvascular construct may prove effective in forming vascularized tissue environments and limiting the number of activated macrophages around implanted polymers thereby leading to effective implant incorporation.

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Section: Resultssupporting

confidence: 89%

Encapsulation of ePTFE in prevascularized collagen leads to peri‐implant vascularization with reduced inflammation

Gruionu

Stone

Schwartz

et al. 2010

J Biomedical Materials Res

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“…Another explanation may be that vascular structures promote incorporation of the implant 46. This relationship between vascular structures and capsule formation is demonstrated in a recent in vivo study by Sanders et al,33 in which single polypropylene fibers, with different diameters ranging from 2.1 to 26.7 μm, were implanted in rats.…”

Section: Discussionmentioning

confidence: 91%

Pore size in implanted polypropylene filters is critical for tissue organization

Rosengren

Bjursten

2003

J Biomedical Materials Res

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Widely different implant materials induce surprisingly similar tissue reactions in vivo in contrast to their in vitro responses. Increasing attention has recently been given to the surface texture of the material. When both the material composition and the surface topography are varied, the surface topography seems to be the predominant factor for the induced tissue response. The present study addresses differences in the tissue response to commercially available Millipore mesh filters of polypropylene with pore sizes of 0.6, 10.0 or 30.0 microm. The Millipore filters with adjacent tissue were directly sectioned in a cryostat and evaluated via an immunofluorescence technique with double and triple staining, allowing simultaneous analysis of different antigens in tissue sections. These results show that macrophages, total cells, necrotic cells, nitric oxygen distribution, early angiogenesis, and capsule thickness were influenced by the surface structure. Implants with pore sizes of 0.6 microm, where entrance of inflammatory cells was inhibited, induce the most pronounced foreign body capsule formation. The 10- and 30-microm filters, in contrast, had large amounts of macrophages inside the filter structure, although very few inflammatory cells were found outside the filters. The inflammatory cells within the filters appeared not to influence the foreign body capsule induction. The critical factor for the formation of a foreign body capsule seems to be the localization of implant-close macrophages. Whether this is due to differences in cell activation or in signal transduction to collagen-synthesizing fibroblasts remains an open question.

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“…The foreign body response that leads to the formation of a relatively avascular capsule varies significantly by tissue type [5, –7]. For example, implants placed in lean tissues have very different healing responses than the same implants in fat [8, –10]. Specifically, implants in rat subcutaneous lean tissue lead to the formation of extensive fibrous capsules as well as reduced vascularity in the tissue adjacent to the implants.…”

Section: Introductionmentioning

confidence: 99%

IFATS Collection: Adipose-Derived Stromal Cells Improve the Foreign Body Response

2008

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Many implanted devices fail due to the formation of an avascular capsule surrounding the device. Additionally, fat has long been known to promote healing and vascularization. The goals of this study were to identify potential mechanisms of the provascular actions of adiposederived stromal cells (ASCs) and to improve implant biocompatibility. First, adult ASCs and fibroblasts from rats were attached to polyurethane and polystyrene in vitro and their cytokine secretion profile was analyzed. Secretion of vascular endothelial growth factor (VEGF) from ASCs was 10 -70 times higher than fibroblasts after 3 and 6 days. Next, polyurethane, bare and with cellular coatings, was implanted subcutaneously in rats. The fibrous capsule surrounding bare polyurethane implants was 17%-32% thicker and the amount of collagen was 27% greater than the capsule surrounding ASC-coated implants. Finally, the microvessel density adjacent to ASC-coated polyurethane was approximately 50%-80% higher than bare polyurethane. In summary, ASCs attached to polyurethane have a dramatically increased VEGF production compared with fibroblasts in vitro, and these cells also produce an increased microvessel density in the surrounding tissue when implanted subcutaneously in rats.

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Differential healing and neovascularization of ePTFE implants in subcutaneous versus adipose tissue

Cited by 39 publications

References 12 publications

Encapsulation of ePTFE in prevascularized collagen leads to peri‐implant vascularization with reduced inflammation

Encapsulation of ePTFE in prevascularized collagen leads to peri‐implant vascularization with reduced inflammation

Pore size in implanted polypropylene filters is critical for tissue organization

IFATS Collection: Adipose-Derived Stromal Cells Improve the Foreign Body Response

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