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Resorbable synthetic scaffolds are promising for different indications, espe- cially in the context of bone regeneration. However, they require additional biological components to enhance their osteogenic potential. In addition to different cell types, autologous blood-derived matrices offer many advantages to enhance the regenerative capacity of biomaterials. The present study aimed to analyze whether biologization of a PCL-mesh coated using differently centrifuged Platelet rich fibrin (PRF) matrices will have a positive influence on primary human osteoblasts activity in vitro. A polymeric resorbable scaffold (Osteomesh, OsteoporeTM (OP), Singapore) was combined with differently centrifuged PRF matrices to evaluate the additional influence of this biologization concept on bone regeneration in vitro. Peripheral blood of three healthy donors was used to gain PRF matrices centrifuged either at High (710× g, 8 min) or Low (44× g, 8 min) relative centrifugal force (RCF) according to the low speed centrifugation concept (LSCC). OP-PRF constructs were cultured with pOBs. POBs cultured on the uncoated OP served as a control. After three and seven days of cultivation, cell culture supernatants were collected to analyze the pOBs activity by determining the concentrations of VEGF, TGF-β1, PDGF, OPG, IL-8, and ALP- activity. Immunofluorescence staining was used to evaluate the Osteopontin expression of pOBs. After three days, the group of OP+PRFLow+pOBs showed significantly higher expression of IL-8, TGF-ß1, PDGF, and VEGF compared to the group of OP+PRFHigh+pOBs and OP+pOBs. Similar results were observed on day 7. Moreover, OP+PRFLow+pOBs exhibited significantly higher activity of ALP compared to OP+PRFHigh+pOBs and OP+pOBs. Immunofluorescence staining showed a higher number of pOBs adherent to OP+PRFLow+pOBs compared to the groups OP+PRFHigh+pOBs and OP+pOBs. To the best of our knowledge, this study is the first to investigate the osteoblasts activity when cultured on a PRF-coated PCL-mesh in vitro. The presented results suggest that PRFLow centrifuged according to LSCC exhibits autologous blood cells and growth factors, seem to have a significant effect on osteogenesis. Thereby, the combination of OP with PRFLow showed promising results to support bone regeneration. Further in vivo studies are required to verify the results and carry out potential results for clinical translation.
Background and Objective: Macrophages’ cytokine expression and polarization play a substantial role in the host's “destructive” inflammatory response to periodontal and peri‐implant pathogens. This study aimed to evaluate cell viability, anti‐inflammatory activity, and macrophage polarization properties of different cranberry concentrates.
Methods: THP‐1 cells (monocytic line) were treated with phorbol myristic acid to induce macrophage differentiation. Human gingival fibroblasts (HFIB‐G cell line), osteosarcoma‐derived osteoblasts (SAOS‐2 cell line), and induced macrophages were treated with cranberry concentrates at 25, 50, and 100 µg/mL for 120 seconds, 1 hour and 24 hours. Untreated cells at the same time points served as controls. For anti‐inflammatory analysis, induced macrophages exposed to cranberry concentrates (A‐type PACs) were stimulated with lipopolysaccharides (LPS) derived from E coli for 24 hours. Cell viability, interleukin (IL)‐8, IL‐1 ß, IL‐6, and IL‐10 expression of LPS‐stimulated macrophages, and macrophage polarization markers were evaluated through determination of live‐cell protease activity, enzyme‐linked immunosorbent assay, and immunofluorescence staining semi‐quantification.
Results: Cranberry concentrates (A‐type PACs) did not reduce HGF, SAOS‐2, and macrophage viability after 24 hours of exposure. Pro‐inflammatory cytokine expression (ie IL‐8 and IL‐6) was downregulated in LPS‐stimulated macrophages by cranberry concentrates at 50 and 100 µg/mL. Anti‐inflammatory IL‐10 expression was significantly upregulated in LPS‐stimulated macrophages by cranberry concentrates at 100 µg/mL after 24 hours of exposure. M1 polarization significantly decreased when LPS‐stimulated macrophages were exposed to cranberry concentrates. High levels of positive M1 macrophages were present in all untreated control groups. M2 polarization significantly increased at all LPS‐stimulated macrophages exposed to cranberry concentrates for 1 and 24 hours.
Conclusion: Cranberry‐derived proanthocyanidins may have the potential to act as an anti‐inflammatory component in the therapy of periodontal and peri‐implant diseases.
Different tissue engineering techniques are used to support rapid vascularisation. A novel technique is the use of platelet-rich fibrin (PRF), an autologous source of growth factors. This study was the first to investigate the influence of PRF matrices, isolated following different centrifugation protocols, on human dermal vascular endothelial cells (ECs) in mono-culture and co-culture with human primary fibroblasts (HFs) as an in vitro model for tissue regeneration. Focus was placed on vascular structure formation and growth factor release. HFs and ECs were cultivated with PRF prepared using a high (710 ×g) or low (44 ×g) relative centrifugation force (RCF) over 14 d. Immunofluorescence staining and immunohistochemistry were used to evaluate the microvascular formation. Cell culture supernatants were collected for evaluation of growth factor release. The results showed a PRF-mediated effect on the induction of angiogenesis in ECs. Microvessel-like structure formation was promoted when ECs were combined with low-RCF PRF as compared to high-RCF PRF or control group. The percentage of vascular lumen area was significantly higher in low-RCF PRF, especially at day 7, which coincided with statistically significantly higher growth factor [vascular endothelial factor (VEGF), transforming growth factor β1 (TGF-β1) and platelet derived growth factor (PDGF)] concentration measured in low-RCF PRF as compared to high-RCF PRF or control group. In conclusion, reducing the RCF according to the low-speed centrifugation concept (LSCC) resulted in increased growth factor release and angiogenic structure formation with EC mono-culture, suggesting that PRF may be a highly beneficial therapeutic tool for tissue engineering applications.
Cellular response of human osteoblasts to different presentations of deproteinized bovine bone
(2022)
Objectives: This study evaluated the cellular response of primary osteoblasts exposed to two different presentations of a low-temperature non-sintered deproteinized bovine bone matrix (DBBM). Materials and methods: Six different baths of a commercially available DBBM block (Bonefill® Porous Block) and one of DBBM granule (Bonefill® Porous) were evaluated to identify the mineral structure and organic or cellular remnants. Samples of the same baths were processed in TRIZOL for RNA extraction and quantification. For the immunologic cell reaction assay, primary human osteoblasts (pOB) were exposed to DBMM block (pOB + B) or granules (pOB + G), or none (control) for 1, 3, or 7 days of cell cultivation. Expression of proinflammatory cytokines by pOB was evaluated by crosslinked ELISA assay. In addition, total DNA amount, as well as cell viability via LDH evaluation, was assessed. Results: Organic remnants were present in DBBM blocks; 45.55% (±7.12) of osteocytes lacunae presented cellular remnants in blocks compared to 17.31% (±1.31) in granules. In three of five batches of blocks, it was possible to isolate bovine RNA. The highest concentration of TGF-β1 was found in supernatants of pOB + G on day 7 (218.85 ± 234.62 pg/mL) (p < 0.05), whereas pOB + B presented the lowest amount of TGF-β1 secretion at the end of evaluation (30.22 ± 14.94 pg/mL, p < 0.05). For IL-6 and OPG, there was no statistical difference between groups, while pOB + G induced more IL-8 secretion than the control (3.03 ± 3.38 ng/mL, p < 0.05). Considering the kinetics of cytokine release during the study period, all groups presented a similar pattern of cytokines, estimated as an increasing concentration for IL-6, IL-8, and OPG during cultivation. Adherent cells were observed on both material surfaces on day 7, according to H&E and OPN staining. Conclusion: Neither tested material induced a pronounced inflammatory response upon osteoblast cultivation. However, further studies are needed to elucidate the potential influence of organic remnants in bone substitute materials on the regeneration process.
The combination of histological and biomolecular analyses provides deep understanding of different biological processes and is of high interest for basic and applied research. However, the available analytical methods are still limited, especially when considering bone samples. This study compared different fixation media to identify a sufficient analytical method for the combination of histological, immuno-histological and biomolecular analyses of the same fixed, processed and paraffin embedded bone sample. Bone core biopsies of rats’ femurs were fixed in different media (RNAlater + formaldehyde (R + FFPE), methacarn (MFPE) or formaldehyde (FFPE)) for 1 week prior to decalcification by EDTA and further histological processing and paraffin embedding. Snap freezing (unfixed frozen tissue, UFT) and incubation in RNAlater were used as additional controls. After gaining the paraffin sections for histological and immunohistological analysis, the samples were deparaffined and RNA was isolated by a modified TRIZOL protocol. Subsequently, gene expression was evaluated using RT-qPCR. Comparable histo-morphological and immuno-histological results were evident in all paraffin embedded samples of MFPE, FFPE and R + FFPE. The isolated RNA in the group of MFPE showed a high concentration and high purity, which was comparable to the UFT and RNAlater groups. However, in the groups of FFPE and R + FFPE, the RNA quality and quantity were statistically significantly lower when compared to MFPE, UFT and RNAlater. RT-qPCR results showed a comparable outcome in the group of MFPE and UFT, whereas the groups of FFPE and R + FFPE did not result in a correctly amplified gene product. Sample fixation by means of methacarn is of high interest for clinical samples to allow a combination of histological, immunohistological and biomolecular analysis. The implementation of such evaluation method in clinical research may allow a deeper understanding of the processes of bone formation and regeneration.