New Models for Patient-specific Evaluation of the Effect of Biomaterials on Macrophages

Biomaterials are often used in many fields of medicine to restore or replace tissue. These biomaterials always elicit a reaction of the immune system, called the foreign body reaction, which can lead to complications in patients and failure of the device. Macrophages are key players in this reaction. Because the foreign body reaction depends on the type and consistency of biomaterials but also on the patient itself, a tailor-made model will be of great help to assess the best treatment. Therefore the ultimate aim of our research was to develop a tailor-made model. Much research has already been performed on macrophages and biomaterials, therefore we started with a literature research of what is already known. First a systematic review of in vitro models describing the macrophage polarisation (pro- (M1) or anti-inflammatory (M2)) in response to different biomaterials was performed (Chapter 2). It was found that many factors are influencing this polarisation such as chemistry, pore size and surface topography. Also sterilisation and chemically crosslinking will alter the macrophage polarisation. However, since many different culture conditions were used, it was difficult to compare the biomaterials. Since we eventually aimed for a tailor-made model, the development of an in vitro model with human isolated macrophages from blood was initiated (Chapter 3). First, distinguishing genes and cytokines for polarisation were determined. These read-out parameters were used for investigating the influence of four different biomaterials on macrophage polarisation; the model showed biomaterial-dependent differences. Macrophages on polypropylene had a phenotype comparable to M2, while macrophages on polyethylene terephthalate and on a combined biomaterial Parietex™ Composite (polyethylene terephthalate and collagen) had a phenotype similar to M1. Macrophages on a collagen biomaterial (Permacol™) produced a low amount of proteins and therefore did not have a clear phenotype. This model can be useful in the future to predict the in vivo outcome of biomaterials. Most research is performed in a sterile environment. However some anatomical locations in the human body are not sterile, like in bowel surgery or rhinoplasty as described in the case report in the introduction. The use of biomaterials in these fields has an increased risk of complications, such as infection [5]. In Chapter 4a an in vivo animal model was used in which a contaminated environment was created by puncture of the bowel, creating a peritonitis to compare the performance of different biomaterials. Six different synthetic and one biological biomaterial were implanted in the abdominal wall. Significant differences in infection rate and incorporation between materials were found. Most infections occurred in C-QurTM and Dualmesh®. The incorporation of the biological mesh (Strattice®) was less than the other synthetic biomaterials, however this mesh was never infected. Dualmesh® showed the most shrinkage. In Chapter 4b samples of the previous study were used to analyse the subtype of macrophages. Parietene CompositeTM and SeprameshTM induced more iNOS-positive cells (M1 polarisation) and C-QurTM and Dualmesh® were surrounded by more CD206-positive cells (M2 polarisation), finding biomaterial-dependent differences in this in vivo rat model. The biomaterial-dependent polarisation of macrophages in a contaminated environment in the rat study inspired to modify the culture model developed in Chapter 3. Inflammatory cytokines (LPS and IFNγ) were added to our in vitro model in Chapter 5, to mimic an inflammatory environment. Polypropylene again stimulated M2 polarisation and Parietex™ Composite and polyethylene terephthalate stimulated an M1 reaction. Despite inflammation, macrophages still behaved bThe foreign body reaction differs per biomaterial and per patient. Some patients have complications after implantation of a biomaterial and some have none with the same biomaterial. For clinical practice, it would be a great benefit to have a tailor-made model with patients own cells to test pre-operatively which biomaterial is best thereby reducing complication rates. Since most of the knowledge and use of biomaterials is in general surgery, we will focus our research in this field. The ultimate goal of our research is to develop a tailor-made _in vitro_ model with human macrophages. Towards developing this model, the following aims are formulated: 1) to develop an _in vitro_ model to study the effect of biomaterials on human macrophage polarisation 2) to investigate the influence of biomaterials on macrophage phenotype in an inflammatory environment and whether this is biomaterial-dependent 3) to investigate the influence of biomaterials on stem cells and macrophages together in an adjusted _in vitro_ mode

Biomaterials Influence Macrophage-Mesenchymal Stem Cell Interaction In Vitro

Background: Macrophages and mesenchymal stem cells (MSCs) are important cells in wound healing. We hypothesized that the cross-talk between macrophages and adipose tissue-derived MSCs (ASCs) is biomaterial dependent, thereby influencing processes involved in wound healing. Materials and Methods: The effect of macrophages cultured on polypropylene (PP) or polyethylene terephthalate coated with a collagen film (PET/Col) on ASCs in monolayer or on the same material was examined either through conditioned medium (CM) or in a direct coculture. ASC proliferation, collagen production, and gene expression were examined. As comparison, the effect of macrophages stimulated with lipopolysaccharide (LPS) and interferon gamma (IFN gamma) [M(LPS/IFN gamma)] or interleukin (IL) 4 [M(IL-4)] on ASCs was examined. Results: Macrophage-CM increased collagen deposition, proliferation, and gene expression of MMP1, PLOD2, and PTGS2 in ASCs, irrespective of the material. Culturing ASCs and macrophages in coculture when only macrophages were on the materials induced the same effects on gene expression. When both ASCs and macrophages were cultured on biomaterials, PP induced COL1A1 and MMP1 more than PET/Col. M(LPS/IFN gamma) CM increased PLOD2, MMP1, and PTGS2 and decreased TGFB in ASCs more than the M(IL-4) CM. Conclusion: Biomaterials influence wound healing by influencing the interaction between macrophages and ASCs. We provided more insight into the behavior of different cell types during wound healing. This behavior appears to be biomaterial specific depending on which cell type interacts with the biomaterial. As such, the biomaterial will influence tissue regeneration

Biomaterials Influence Macrophage-Mesenchymal Stem Cell Interaction In Vitro

Background: Macrophages and mesenchymal stem cells (MSCs) are important cells in wound healing. We hypothesized that the cross-talk between macrophages and adipose tissue-derived MSCs (ASCs) is biomaterial dependent, thereby influencing processes involved in wound healing. Materials and Methods: The effect of macrophages cultured on polypropylene (PP) or polyethylene terephthalate coated with a collagen film (PET/Col) on ASCs in monolayer or on the same material was examined either through conditioned medium (CM) or in a direct coculture. ASC proliferation, collagen production, and gene expression were examined. As comparison, the effect of macrophages stimulated with lipopolysaccharide (LPS) and interferon gamma (IFN gamma) [M(LPS/IFN gamma)] or interleukin (IL) 4 [M(IL-4)] on ASCs was examined. Results: Macrophage-CM increased collagen deposition, proliferation, and gene expression of MMP1, PLOD2, and PTGS2 in ASCs, irrespective of the material. Culturing ASCs and macrophages in coculture when only macrophages were on the materials induced the same effects on gene expression. When both ASCs and macrophages were cultured on biomaterials, PP induced COL1A1 and MMP1 more than PET/Col. M(LPS/IFN gamma) CM increased PLOD2, MMP1, and PTGS2 and decreased TGFB in ASCs more than the M(IL-4) CM. Conclusion: Biomaterials influence wound healing by influencing the interaction between macrophages and ASCs. We provided more insight into the behavior of different cell types during wound healing. This behavior appears to be biomaterial specific depending on which cell type interacts with the biomaterial. As such, the biomaterial will influence tissue regeneration

The Effect of Biomaterials Used for Tissue Regeneration Purposes on Polarization of Macrophages

Activation of macrophages is critical in the acute phase of wound healing after implantation of surgical biomaterials. To understand the response of macrophages, they are often cultured in vitro on biomaterials. Since a wide range of biomaterials is currently used in the clinics, we undertook a systematic review of the macrophage polarization in response to these different surgical biomaterials in vitro. Beside the chemistry, material characteristics such as dimension, pore size, and surface topography are of great influence on the response of macrophages. The macrophage response also appears to depend on the differences in sterilization techniques that induce lasting biochemical changes or residues of chemicals and their byproducts used for sterilization. Regarding tissue-based biomaterials, macrophages on human or porcine dermis, strongly cross-linked by chemicals elicit in general a proinflammatory response with higher amounts of proinflammatory cytokines. Synthetic biomaterials such as polyethylene, polyethylene terephthalate (PET) + polyacrylamide (PAAm), PET + sodium salt of poly(acrylic acid) (PAANa), perfluoropolyether (PFPE) with large posts, PEG-g-PA, and polydioxanone (PDO) always appear to elicit an anti-inflammatory response in macrophages, irrespective of origin of the macrophages, for example, buffy coats or full blood. In conclusion, in general in vitro models contribute to evaluate the foreign body reaction on surgical biomaterials. Although it is difficult to simulate complexity of host response elicited by biomaterials, after their surgical implantation, an in vitro model gives indications of the initial foreign body response and allows the comparison of this response between biomaterials

Biomaterials Influence Macrophage-Mesenchymal Stem Cell Interaction In Vitro

Background: Macrophages and mesenchymal stem cells (MSCs) are important cells in wound healing. We hypothesized that the cross-talk between macrophages and adipose tissue-derived MSCs (ASCs) is biomaterial dependent, thereby influencing processes involved in wound healing. Materials and Methods: The effect of macrophages cultured on polypropylene (PP) or polyethylene terephthalate coated with a collagen film (PET/Col) on ASCs in monolayer or on the same material was examined either through conditioned medium (CM) or in a direct coculture. ASC proliferation, collagen production, and gene expression were examined. As comparison, the effect of macrophages stimulated with lipopolysaccharide (LPS) and interferon gamma (IFNγ) [M(LPS/IFNγ)] or interleukin (IL) 4 [M(IL-4)] on ASCs was examined. Results: Macrophage-CM increased collagen deposition, proliferation, and gene expression of MMP1, PLOD2, and PTGS2 in ASCs, irrespective of the material. Culturing ASCs and macrophages in coculture when only macrophages were on the materials induced the same effects on gene expression. When both ASCs and macrophages were cultured on biomaterials, PP induced COL1A1 and MMP1 more than PET/Col. M(LPS/IFNγ) CM increased PLOD2, MMP1, and PTGS2 and decreased TGFB in ASCs more than the M(IL-4) CM. Conclusion: Biomaterials influence wound healing by influencing the interaction between macrophages and ASCs. We provided more insight into the behavior of different cell types during wound healing. This behavior appears to be biomaterial specific depending on which cell type interacts with the biomaterial. As such, the biomaterial will influence tissue regeneration

New Models for Patient-specific Evaluation of the Effect of Biomaterials on Macrophages

Biomaterials are often used in many fields of medicine to restore or replace tissue. These biomaterials always elicit a reaction of the immune system, called the foreign body reaction, which can lead to complications in patients and failure of the device. Macrophages are key players in this reaction. Because the foreign body reaction depends on the type and consistency of biomaterials but also on the patient itself, a tailor-made model will be of great help to assess the best treatment. Therefore the ultimate aim of our research was to develop a tailor-made model. Much research has already been performed on macrophages and biomaterials, therefore we started with a literature research of what is already known. First a systematic review of in vitro models describing the macrophage polarisation (pro- (M1) or anti-inflammatory (M2)) in response to different biomaterials was performed (Chapter 2). It was found that many factors are influencing this polarisation such as chemistry, pore size and surface topography. Also sterilisation and chemically crosslinking will alter the macrophage polarisation. However, since many different culture conditions were used, it was difficult to compare the biomaterials. Since we eventually aimed for a tailor-made model, the development of an in vitro model with human isolated macrophages from blood was initiated (Chapter 3). First, distinguishing genes and cytokines for polarisation were determined. These read-out parameters were used for investigating the influence of four different biomaterials on macrophage polarisation; the model showed biomaterial-dependent differences. Macrophages on polypropylene had a phenotype comparable to M2, while macrophages on polyethylene terephthalate and on a combined biomaterial Parietex™ Composite (polyethylene terephthalate and collagen) had a phenotype similar to M1. Macrophages on a collagen biomaterial (Permacol™) produced a low amount of proteins and therefore did not have a clear phenotype. This model can be useful in the future to predict the in vivo outcome of biomaterials. Most research is performed in a sterile environment. However some anatomical locations in the human body are not sterile, like in bowel surgery or rhinoplasty as described in the case report in the introduction. The use of biomaterials in these fields has an increased risk of complications, such as infection [5]. In Chapter 4a an in vivo animal model was used in which a contaminated environment was created by puncture of the bowel, creating a peritonitis to compare the performance of different biomaterials. Six different synthetic and one biological biomaterial were implanted in the abdominal wall. Significant differences in infection rate and incorporation between materials were found. Most infections occurred in C-QurTM and Dualmesh®. The incorporation of the biological mesh (Strattice®) was less than the other synthetic biomaterials, however this mesh was never infected. Dualmesh® showed the most shrinkage. In Chapter 4b samples of the previous study were used to analyse the subtype of macrophages. Parietene CompositeTM and SeprameshTM induced more iNOS-positive cells (M1 polarisation) and C-QurTM and Dualmesh® were surrounded by more CD206-positive cells (M2 polarisation), finding biomaterial-dependent differences in this in vivo rat model. The biomaterial-dependent polarisation of macrophages in a contaminated environment in the rat study inspired to modify the culture model developed in Chapter 3. Inflammatory cytokines (LPS and IFNγ) were added to our in vitro model in Chapter 5, to mimic an inflammatory environment. Polypropylene again stimulated M2 polarisation and Parietex™ Composite and polyethylene terephthalate stimulated an M1 reaction. Despite inflammation, macrophages still behaved

A culture model to analyze the acute biomaterial-dependent reaction of human primary macrophages

Macrophages are important in foreign body reactions. We devised a culture model with human primary macrophages to evaluate the acute response of macrophages to biomaterials. First we selected proteins representative for pro-inflammatory (M1) or anti-inflammatory/repair (M2) response of monocytes isolated from blood of healthy human donors by exposing them to LPS+IFN gamma or IL-4. A relative M1/M2 index was calculated using IL-1 beta, IL-6, tumor necrosis factor (TNF)alpha, monocyte chemotactic protein (MCP)-3 and macrophage inflammatory protein (MIP)-1 alpha as M1 markers, and IL-1 receptor antagonist (IL-1RA), CCL18, regulated and normal T-cell expressed and secreted (RANTES), and macrophage-derived chemokine (MDC) as M2 markers. Then monocytes were cultured for 3 days on 4 materials selected for known different foreign body reactions: Permacol (TM), Parietex (TM) Composite, multifilament polyethylene terephthalate and multifilament polypropylene. Macrophages on polypropylene produced high levels of anti-inflammatory proteins with a low M1 M2 index. Macrophages on Parietex (TM) Composite produced high levels of inflammatory and anti-inflammatory proteins, with a high M1/M2 index. Macrophages on polyethylene terephthalate also resulted in a high M1/M2 index. Macrophages on Permacol (TM) produced a low amount of all proteins, with a low M1/M2 index. This model with human primary macrophages and the panel of read-out parameters can be used to evaluate the acute reaction of macrophages to biomaterials in vitro to get more insight in the foreign body reaction. (c) 2013 Elsevier Inc. All rights reserved

Biomaterials Influence Macrophage-Mesenchymal Stem Cell Interaction In Vitro

Background: Macrophages and mesenchymal stem cells (MSCs) are important cells in wound healing. We hypothesized that the cross-talk between macrophages and adipose tissue-derived MSCs (ASCs) is biomaterial dependent, thereby influencing processes involved in wound healing. Materials and Methods: The effect of macrophages cultured on polypropylene (PP) or polyethylene terephthalate coated with a collagen film (PET/Col) on ASCs in monolayer or on the same material was examined either through conditioned medium (CM) or in a direct coculture. ASC proliferation, collagen production, and gene expression were examined. As comparison, the effect of macrophages stimulated with lipopolysaccharide (LPS) and interferon gamma (IFN gamma) [M(LPS/IFN gamma)] or interleukin (IL) 4 [M(IL-4)] on ASCs was examined. Results: Macrophage-CM increased collagen deposition, proliferation, and gene expression of MMP1, PLOD2, and PTGS2 in ASCs, irrespective of the material. Culturing ASCs and macrophages in coculture when only macrophages were on the materials induced the same effects on gene expression. When both ASCs and macrophages were cultured on biomaterials, PP induced COL1A1 and MMP1 more than PET/Col. M(LPS/IFN gamma) CM increased PLOD2, MMP1, and PTGS2 and decreased TGFB in ASCs more than the M(IL-4) CM. Conclusion: Biomaterials influence wound healing by influencing the interaction between macrophages and ASCs. We provided more insight into the behavior of different cell types during wound healing. This behavior appears to be biomaterial specific depending on which cell type interacts with the biomaterial. As such, the biomaterial will influence tissue regeneration

Experimental study on synthetic and biological mesh implantation in a contaminated environment

Background: Implantation of meshes in a contaminated environment can be complicated by mesh infection and adhesion formation. Methods: The caecal ligation and puncture model was used to induce peritonitis in 144 rats. Seven commercially available meshes were implanted intraperitoneally: six non-absorbable meshes, of which three had an absorbable coating, and one biological mesh. Mesh infection, intra-abdominal abscess formation, adhesion formation, incorporation and shrinkage were evaluated after 28 and 90 days. Histological examination with haematoxylin and eosin and picrosirius red staining was performed. Results: No mesh infections occurred in Sepramesh (R), Omyramesh (R) and Strattice (R). One mesh infection occurred in Parietene (R) and Parietene Composite (R). Significantly more mesh infections were found in C-Qur (R) (15 of 16; P <= 0.006) and Dualmesh (R) (7 of 15; P <= 0.035). Sepramesh (R) showed a significant increase in adhesion coverage from 12.5 per cent at 28 days to 60.0 per cent at 90 days (P = 0.010). At 90 days there was no significant difference between median adhesion coverage Conclusion: Parietene Composite (R) and Omyramesh (R) performed well in a contaminated environment. Strattice (R) had little adhesion formation and no mesh infection, but poor incorporation. Some synthetic meshes can be as resistant to infection as biological meshes. Copyright (c) 2012 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd