A comparative multi-parametric in vitro model identifies the power of test conditions to predict the fibrotic tendency of a biomaterial

Abstract

Despite growing effort to advance materials towards a low fibrotic progression, all implants elicit adverse tissue responses. Pre-clinical biomaterial assessment relies on animals testing, which can be complemented by in vitro tests to address the Russell and Burch’s 3R aspect of reducing animal burden. However, a poor correlation between in vitro and in vivo biomaterial assessments confirms a need for suitable in vitro biomaterial tests. The aim of the study was to identify a test setting, which is predictive and might be time- and cost-efficient. We demonstrated how sensitive in vitro biomaterial assessment based on human primary macrophages depends on test conditions. Moreover, possible clinical scenarios such as lipopolysaccharide contamination, contact to autologous blood plasma, and presence of IL-4 in an immune niche influence the outcome of a biomaterial ranking. Nevertheless, by using glass, titanium, polytetrafluorethylene, silicone, and polyethylene representing a specific material-induced fibrotic response and by comparison to literature data, we were able to identify a test condition that provides a high correlation to state-of-the-art in vivo studies. Most important, biomaterial ranking obtained under native plasma test conditions showed a high predictive accuracy compared to in vivo assessments, strengthening a biomimetic three-dimensional in vitro test platform.

Macrophage and Fibroblast Interactions in Biomaterial‐Mediated Fibrosis

“…Recent studies have demonstrated the utility of 3D in vitro systems and biomaterial platforms to aid in studying the complex mechanotransduction, phenotypic changes, and signaling between macrophages and fibroblasts. Jannasch et al embedded fibroblasts within a 3D collagen hydrogel incubated in media derived from macrophages cultured on various biomaterial surfaces (glass, titanium, and polytetrafluoroethylene (PTFE)) . Live cell imaging combined with computational modeling allowed the authors to determine the chemotactic potential of the fibroblasts and long‐term behavior of fibroblasts within the 3D collagen matrix environment .…”

“…Jannasch et al embedded fibroblasts within a 3D collagen hydrogel incubated in media derived from macrophages cultured on various biomaterial surfaces (glass, titanium, and polytetrafluoroethylene (PTFE)) . Live cell imaging combined with computational modeling allowed the authors to determine the chemotactic potential of the fibroblasts and long‐term behavior of fibroblasts within the 3D collagen matrix environment . Fibroblasts were significantly more motile within the hydrogel when cultured in conditioned media derived from macrophages cultured on titanium compared to conditioned media derived from macrophages cultured on glass or PTFE.…”

“…Fibroblasts were significantly more motile within the hydrogel when cultured in conditioned media derived from macrophages cultured on titanium compared to conditioned media derived from macrophages cultured on glass or PTFE. On the other hand, fibroblasts cultured in conditioned media derived from macrophages cultured on PTFE demonstrated significantly greater remodeling capacity, evidenced by increased collagen fibril deposition and organization within the hydrogel, compared to the other conditions . Lastly, Caires et al demonstrated the utility of a 3D coculture system to examine the interdependent effects of macrophages, fibroblasts, and MSCs on cell migration in response to poly(lactic acid) scaffolds or chitosan scaffolds .…”

Nanotopographical Coatings Induce an Early Phenotype-Specific Response of Primary Material-Resident M1 and M2 Macrophages

“…A standard protocol was performed for immunohistochemical staining on the biomaterial surfaces, as described in [3]. Briefly, cells were fixed with 4% paraformaldehyde (Carl Roth, Karlsruhe, Germany) for 10 min at room temperature.…”

“…Thus, the FBR is a key factor in the long-term survival and function of an implanted biomaterial [2]. During the FBR, macrophages play a major role [3,4]. Over time, an initial population of short-lived pro-inflammatory M1 macrophages is replaced by long-vitae M2 macrophages.…”