On the mechanism of poly(methacrylic acid –co– methyl methacrylate)-induced angiogenesis: Gene expression analysis of dTHP-1 cells

Hydrogel Arrays and Choroidal Neovascularization Models for Evaluation of Angiogenic Activity of Vital Pulp Therapy Biomaterials

INTRODUCTION

This study intended to evaluate the angiogenic properties of vital pulp therapy materials including white mineral trioxide aggregate (WMTA), calcium hydroxide (Ca[OH]2), Geristore (Den-Mat, Santa Maria, CA), and nano WMTA biomaterials.

METHODS

WMTA, Ca(OH)2, Geristore, and nano WMTA disks were prepared, dispersed into 2 mL Milli-Q (Millipore, ThermoFisher, Hanover Park, IL) distilled water, and centrifuged to obtain 2 mL supernatant elution. Thirty-five wells of polyethylene glycol hydrogel arrays were prepared and divided into 5 groups of 7 (n = 7). Mice molar endothelial cells (ECs) were placed on hydrogel arrays. The elution prepared from each sample was diluted in growth medium (1:3) and added to the hydrogel arrays. The EC medium alone was used for the control. For the choroidal neovascularization (CNV) model, thirty-five 6-week-old female mice were lasered and divided into 5 groups, and elution from each sample (2 μL) or saline (control) was delivered by intravitreal injection on the day of the laser treatment and 1 week later. The mean number of nodes, the total length of the branches in the hydrogel arrays, and the mean area of CNV were calculated using ImageJ software (National Institutes of Health, Bethesda, MD) and analyzed by 1-way analysis of variance and post hoc Tukey honest significant difference tests.

RESULTS

The comparison of results regarding the number of nodes showed the values of control > Geristore > nano WMTA > WMTA > Ca(OH)2. Regarding the total branch length and the CNV area, the comparison of results showed values of Geristore > control > nano WMTA > WMTA > Ca(OH)2.

CONCLUSIONS

All tested materials showed minimal antiangiogenic activity, whereas Geristore and nano WMTA showed a higher proangiogenic activity than WMTA and Ca(OH)2.

The role of insulin growth factor-1 on the vascular regenerative effect of MAA coated disks and macrophage-endothelial cell crosstalk

The IGF-1 signaling pathway and IGF-1-dependent macrophage/endothelial cell crosstalk was found to be critical features of the vascular regenerative effect displayed by implanted methacrylic acid -co-isodecyl acrylate (MAA-co-IDA; 40% MAA) coated disks in CD1 mice. Inhibition of IGF-1 signaling using AG1024 an IGF1-R tyrosine kinase inhibitor abrogated vessel formation 14 days after disk implantation in a subcutaneous pocket. Explanted tissue had increased arginase 1 expression and reduced iNOS expression consistent with the greater shift from "M1" ("pro-inflammatory") macrophages to "M2" ("pro-angiogenic") macrophages for MAA coated disks relative to control MM (methyl methacrylate-co-IDA) disks; the latter did not generate a vascular response and the polarization shift was muted with AG1024. In vitro, medium conditioned by macrophages (both human dTHP1 cells and mouse bone marrow derived macrophages) had elevated IGF-1 mRNA and protein levels, while the cells had reduced IGF1-R but elevated IGFBP-3 mRNA levels. These cells also had reduced iNOS and elevated Arg1 expression, consistent with the in vivo polarization results, including the inhibitory effects of AG1024. On the other hand, HUVEC exposed to dTHP1 conditioned medium migrated and proliferated faster suggesting that the primary target of the macrophage released IGF-1 was endothelial cells. Although further investigation is warranted, IGF-1 appears to be a key feature underpinning the observed vascularization. Why MAA based materials have this effect remains to be defined, however.

Molecular finds of pressure ulcer: A bioinformatics approach in pressure ulcer

BACKGROUND

Understanding the biological processes underlying Pressure Ulcer (PU) is an important strategy to identify new molecular targets. Bioinformatics has emerged as an important screening tool for a broad range of diseases.

OBJECTIVE

This study aim of the current study is to investigate the protein-protein interaction in the PU context by bioinformatics.

METHODS

We performed a search in gene databases, and bioinformatics algorithms were used to generate molecular targets for PU based in silico investigation. Interactions networks between protein-coding genes were built and compared to skin.

RESULTS

TNFA, MMP9, and IL10 genes have higher disease-related connectivity than a connectivity general global. MAGOH, UBC, and PTCH1 as were leader genes related to skin. Ontological analysis demonstrated different mechanisms associated, such as response to oxidase stress.

CONCLUSION

TNFA, MMP9, and IL10 are possible therapeutic targets for pressure ulcer. Additional investigation of cell post-transcriptional machinery should be investigated in PU.

Effect of methacrylic acid beads on the sonic hedgehog signaling pathway and macrophage polarization in a subcutaneous injection mouse model

Poly(methacrylic acid-co-methyl methacrylate) (MAA) beads promote a vascular regenerative response when used in diabetic wound healing. Previous studies reported that MAA beads modulated the expression of sonic hedgehog (Shh) and inflammation related genes in diabetic wounds. The aim of this work was to follow up on these observations in a subcutaneous injection model to study the host response in the absence of the confounding factors of diabetic wound healing. In this model, MAA beads improved vascularization in healthy mice of both sexes compared to control poly(methyl methacrylate) (MM) beads, with a stronger effect seen in males than females. MAA-induced vessels were perfusable, as evidenced from the CLARITY-processed images. In Shh-Cre-eGFP/Ptch1-LacZ non-diabetic transgenic mice, the increased vessel formation was accompanied by a higher density of cells expressing GFP (Shh) and β-Gal (patched 1, Ptch1) suggesting MAA enhanced the activation of the Shh pathway. Ptch1 is the Shh receptor and a target of the pathway. MAA beads also modulated the inflammatory cell infiltrate in CD1 mice: more neutrophils and more macrophages were noted with MAA relative to MM beads at days 1 and 7, respectively. In addition, MAA beads biased macrophages towards a MHCII-CD206+ ("M2") polarization state. This study suggests that the Shh pathway and an altered inflammatory response are two elements of the complex mechanism whereby MAA-based biomaterials effect vascular regeneration.

Cell Interactions with Vascular Regenerative MAA-Based Materials in the Context of Wound Healing

In diabetic patients the development of chronic non-healing wounds is a common complication. A methacrylic acid-based biomaterial is a vascular regenerative material that enhances diabetic healing without the use of cells or growth factors. The bioactive nature of this material is thought to be associated with its anionic charge or surface chemistry. Contact between the methacrylic acid-based biomaterial and tissue begins with protein (including complement) adsorption and is followed by interaction of the biomaterial with resident and infiltrating cells in the wound bed (e.g., macrophages and endothelial cells). This results in changes to their surface receptors to activate phosphorylation cascades that lead to differential activation of signalling pathways such as those involving osteopontin and sonic hedgehog. These changes modulate the phenotype of the cells in the wound bed, eventually improving vessel formation and wound healing. Understanding the molecular and cellular mechanisms will have broad implications for biomaterials, not just the methacrylic acid-based material, and will facilitate the advancement of regenerative biomaterials for diverse applications.

Interaction of a block-co-polymeric biomaterial with immunoglobulin G modulates human monocytes towards a non-inflammatory phenotype

Monocyte interactions with implanted biomaterials can contribute significantly to the ability of a biomaterial to support tissue integration and wound healing, as opposed to a chronic pro-inflammatory foreign body reaction, provided the materials are designed to do so. However, there are few biomaterials available designed to regulate immune cell response with the intention of reducing the pro-inflammatory activation state. Material chemistry is a powerful tool for regulating protein and cell interactions that can be incorporated into surfaces while maintaining desired mechanical properties. The aspects of material chemistry that can support monocyte activation away from a pro-inflammatory state are still poorly understood. Protein adsorption is a key initial event that transforms the surface of a biomedical device into a biological substrate that will govern subsequent cellular interactions. In this study, the chemistry of degradable block polyurethanes, termed degradable polar hydrophobic ionic (D-PHI) polyurethanes, were studied for their unique interactions with bound immunoglobulin G (IgG), a pro-inflammatory protein that supports monocyte-biomaterial interactions. The specific immunological active sites of the polyurethane-adsorbed protein were compared with IgG's adsorbed state on a homopolymeric material with surface chemistry conducive to cell interactions, e.g. tissue culture polystyrene (TCPS). IgG-coated TCPS supported sustained monocyte adhesion and enhanced monocyte spreading, effects not observed with IgG-coated PU. The degradable PU was subsequently shown to reduce the number of exposed IgG-Fab sites following pre-adsorption vs. IgG adsorbed to TCPS, with antibody inhibition experiments demonstrating that Fab-site exposure appears to dominate monocyte-biomaterial interactions. Minor changes in chemical segments within the PU molecular chains were subsequently investigated for their influence on directing IgG interactions towards reducing pro-inflammatory activity. A reduction in chemical heterogeneity within the PU, without significant differences in other material properties known to regulate monocyte response, was shown to increase Fab exposure and subsequently led to monocyte interactions similar to those observed for IgG-coated TCPS. These results infer that reduced IgG-Fab site exposure can be directed by material chemistry to attenuate pro-inflammatory monocyte interactions with biomaterial surfaces, and identify the chemical features of polymeric biomaterial design responsible for this process.

STATEMENT OF SIGNIFICANCE

There is currently limited understanding of material design features that can regulate protein-material interactions in order to prevent adverse inflammatory responses to implanted biomaterials. In this paper, monocyte interactions with biomaterials (specifically a block co-polymeric degradable polyurethane [D-PHI] and tissue culture polystyrene [TCPS]) were investigated as a function of their interactions with adsorbed immunoglobulin G (IgG). D-PHI was shown to attenuate IgG-induced monocyte retention and spreading by reducing IgG-Fab site exposure upon adsorption relative to TCPS. Aspects of D-PHI chemistry important in regulating Fab site exposure were determined. This study thus identifies features of biomaterials, using D-PHI as a case study, which can contribute to the development of new immunomodulatory biomaterial design.

Unbiased phosphoproteomic method identifies the initial effects of a methacrylic acid copolymer on macrophages

An unbiased phosphoproteomic method was used to identify biomaterial-associated changes in the phosphorylation patterns of macrophage-like cells. The phosphorylation differences between differentiated THP1 (dTHP1) cells treated for 10, 20, or 30 min with a vascular regenerative methacrylic acid (MAA) copolymer or a control methyl methacrylate (MM) copolymer were determined by MS. There were 1,470 peptides (corresponding to 729 proteins) that were differentially phosphorylated in dTHP1 cells treated with the two materials with a greater cellular response to MAA treatment. In addition to identifying pathways (such as integrin signaling and cytoskeletal arrangement) that are well known to change with cell-material interaction, previously unidentified pathways, such as apoptosis and mRNA splicing, were also discovered.

Interactions between osteopontin and vascular endothelial growth factor: Implications for cancer

For this comprehensive review, 257 publications with the keywords "osteopontin" or "OPN" and "vascular endothelial growth factor" or "VEGF" in PubMed were screened (time frame from year 1996 to year 2014). 37 articles were excluded because they were not focused on the interactions between these molecules, and papers relevant for transformation-related phenomena were selected. Osteopontin (OPN) and vascular endothelial growth factor (VEGF) are characterized by a convergence in function for regulating cell motility and angiogenesis, the response to hypoxia, and apoptosis. Often, they are co-expressed or one molecule induces the other, however, in some settings OPN-associated pathways and VEGF-associated pathways are distinct. Their relationships affect the pathogenesis in cancer, where they contribute to progression and angiogenesis and serve as markers for poor prognosis. The inhibition of OPN may reduce VEGF levels and suppress tumor progression. In vascular pathologies, these two cytokines mediate remodeling, but may also perpetuate inflammation and narrowing of the arteries. OPN and VEGF are elevated and contribute to vascularization in inflammatory diseases.

Coculture with intraocular lens material-activated macrophages induces an inflammatory phenotype in lens epithelial cells

Cataracts are the leading cause of blindness worldwide, requiring surgical implantation of an intraocular lens. Despite evidence of leukocyte ingress into the postoperative lens, few studies have investigated the leukocyte response to intraocular lens materials. A novel coculture model was developed to examine macrophage activation by hydrophilic acrylic (poly(2-hydroxyethyl methacrylate)) and hydrophobic acrylic (polymethylmethacrylate) commercial intraocular lens. The human monocytic cell line THP-1 was differentiated into macrophages and cocultured with human lens epithelial cell line (HLE-B3) with or without an intraocular lens for one, two, four, or six days. Using flow cytometry and confocal microscopy, expression of the macrophage activation marker CD54 (intercellular adhesion molecule-1) and production of reactive oxygen species via the fluorogenic probe 2',7'-dichlorodihydrofluorescein diacetate were examined in macrophages. α-Smooth muscle actin, a transdifferentiation marker, was characterized in lens epithelial cells. The poly(2-hydroxyethyl methacrylate) intraocular lens prevented adhesion but induced significant macrophage activation (p < 0.03) versus control (no intraocular lens), while the polymethylmethacrylate intraocular lens enabled adhesion and multinucleated fusion, but induced no significant activation. Coculture with either intraocular lens increased reactive oxygen species production in macrophages after one day (p < 0.03) and increased expression of α-smooth muscle actin in HLE B-3 after six days, although only poly(2-hydroxyethyl methacrylate) induced a significant difference versus control (p < 0.01). Our results imply that-contrary to prior uveal biocompatibility understanding-macrophage adherence is not necessary for a strong inflammatory response to an intraocular lens, with hydrophilic surfaces inducing higher activation than hydrophobic surfaces. These findings provide a new method of inquiry into uveal biocompatibility, specifically through the quantification of cell-surface markers of leukocyte activation.

The expression of sonic hedgehog in diabetic wounds following treatment with poly(methacrylic acid-co-methyl methacrylate) beads

The expression of native sonic hedgehog (Shh) was significantly increased in poly(methacrylic acid-co-methyl methacrylate) bead (MAA) treated wounds at day 4 compared to both poly(methyl methacrylate) bead (PMMA) treated and untreated wounds in diabetic db/db mice. MAA beads also increased the expression of the Shh transcription factor Gli3 at day 4. Previously, topical application of MAA beads (45 mol % methacrylic acid) improved wound closure and blood vessel density in excisional wounds in these mice, while PMMA beads did not. Gene expression within the granulation tissue of healing wounds was studied to provide insight into the mechanism of vessel formation and wound healing in the presence of MAA beads. In addition to the increased expression of Shh, MAA-treated wounds had increased expression of osteopontin (OPN), IL-1β and TNF-α, (at day 7) similar to the previously reported MAA response of macrophage-like and endothelial cells in vitro.