Osteogain® loaded onto an absorbable collagen sponge induces attachment and osteoblast differentiation of ST2 cells in vitro

Amelogenin-Derived Peptides in Bone Regeneration: A Systematic Review

Amelogenins are enamel matrix proteins currently used to treat bone defects in periodontal surgery. Recent studies have highlighted the relevance of amelogenin-derived peptides, named LRAP, TRAP, SP, and C11, in bone tissue engineering. Interestingly, these peptides seem to maintain or even improve the biological activity of the full-length protein, which has received attention in the field of bone regeneration. In this article, the authors combined a systematic and a narrative review. The former is focused on the existing scientific evidence on LRAP, TRAP, SP, and C11's ability to induce the production of mineralized extracellular matrix, while the latter is concentrated on the structure and function of amelogenin and amelogenin-derived peptides. Overall, the collected data suggest that LRAP and SP are able to induce stromal stem cell differentiation towards osteoblastic phenotypes; specifically, SP seems to be more reliable in bone regenerative approaches due to its osteoinduction and the absence of immunogenicity. However, even if some evidence is convincing, the limited number of studies and the scarcity of in vivo studies force us to wait for further investigations before drawing a solid final statement on the real potential of amelogenin-derived peptides in bone tissue engineering.

Application of a collagen scaffold saturated with platelet-rich plasma in prevention of bisphosphonate-related osteonecrosis of the jaw in the rat animal model

BACKGROUND

Among the myriad adverse events of drugs in the oral cavity, Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is one of the most detrimental drug reactions that have ever been known.

OBJECTIVE

This study was aimed to investigate the success of applying collagen scaffold alone and platelet-rich plasma (PRP)+collagen scaffold in prevention of zoledronic acid-induced BRONJ in the rat.

METHODS

A total of 17 male Wistar-rats were treated with 4 weekly doses of zoledronic acid. All rats were undergone bilateral tooth extraction of mandibular first molars and divided into three groups of scaffold + PRP + suture, scaffold + suture, and suture only. All rats were scarified and clinical, radiological, histological and histomorphomerical evaluations were made on week 8 post-treatment. The soft tissue healing, bone mineralized density (BMD), number of osteoclasts and osteoblasts, necrotic bone (NB), intensity of inflammation and new bone formation (NBF) were analyzed.

RESULTS

BMD, number of osteoblasts and NBF variables proved to be statistically were higher in the treatment groups than the control group. In addition, the PRP + scaffold group showed the better results in terms of BMD, number of osteoblasts and NBF than that of the scaffold alone group. Number of osteoclasts, inflammation intensity and osteonecrosis were also significantly different in the PRP + scaffold group compared to the scaffold alone and the control groups.

CONCLUSION

Application of a PRP-enriched collagen scaffold appeared to be a successful preventive treatment for BRONJ by effecting of the number of osteoblasts and osteoclasts, BMD, NBF, inflammation, and osteonecrosis.

Which substances loaded onto collagen scaffolds influence oral tissue regeneration?-an overview of the last 15 years

BACKGROUND

Collagen scaffolds are widely used for guided bone or tissue regeneration. Aiming to enhance their regenerative properties, studies have loaded various substances onto these scaffolds. This review aims to provide an overview of existing literature which conducted in vitro, in vivo, and clinical testing of drug-loaded collagen scaffolds and analyze their outcome of promoting oral regeneration.

MATERIALS AND METHODS

PubMed, Scopus, and Ovid Medline® were systematically searched for publications from 2005 to 2019. Journal articles assessing the effect of substances on oral hard or soft tissue regeneration, while using collagen carriers, were screened and qualitatively analyzed. Studies were grouped according to their used substance type-biological medical products, pharmaceuticals, and tissue-, cell-, and matrix-derived products.

RESULTS

A total of 77 publications, applying 36 different substances, were included. Collagen scaffolds were demonstrating favorable adsorption behavior and release kinetics which could even be modified. BMP-2 was investigated most frequently, showing positive effects on oral tissue regeneration. BMP-9 showed comparable results at lower concentrations. Also, FGF2 enhanced bone and periodontal healing. Antibiotics improved the scaffold's anti-microbial activity and reduced the penetrability for bacteria.

CONCLUSION

Growth factors showed promising results for oral tissue regeneration, while other substances were investigated less frequently. Found effects of investigated substances as well as adsorption and release properties of collagen scaffolds should be considered for further investigation.

CLINICAL RELEVANCE

Collagen scaffolds are reliable carriers for any of the applied substances. BMP-2, BMP-9, and FGF2 showed enhanced bone and periodontal healing. Antibiotics improved anti-microbial properties of the scaffolds.

Effect of enamel matrix derivative liquid combined with synthetic bone substitute on bone regeneration in a rabbit calvarial model

OBJECTIVES

This study aimed to verify the effectiveness of EMD-liquid in combination with a synthetic bone substitute in a rabbit calvarial model.

MATERIAL AND METHODS

Four 7-mm outer diameter circular slits were created in the calvaria of 10 New Zealand white rabbits, and polycarbonate cylinders were inserted into the slits. Two experimental groups were established: (1) EMD-liquid + bone substitute (Osteon III®; biphasic calcium phosphate (BCP), β-TCP/HA = 40:60) and (2) saline + bone substitute (Osteon III®; BCP). The cylinders were filled with saturated graft materials and covered with polycarbonate caps. Micro-CT and histomorphometric evaluation were conducted.

RESULTS

In the histomorphometric analysis, new bone formation was significantly higher in the bone substitute (BS) + EMD-liquid group than in the BS only group at both 5 and 10 weeks (p < 0.01). There were statistically significant differences in the material area between the bone substitute and bone substitute + EMD-liquid groups at only 5 weeks (p < 0.05). The BS + EMD-liquid group demonstrated reduced material area to a greater extent. In micro-CT analysis, the BS + EMD-liquid group (27.04 ± 8.06 at 5 weeks, 28.49 ± 9.22 at 10 weeks) showed a significantly higher percentage of mineralized tissue volume at both 5 and 10 weeks (p < 0.05) than the BS only group.

CONCLUSION

EMD-liquid enhances new bone formation when combined with BCP bone substitute in an animal model. Moreover, the EMD-liquid + BS has significantly lesser material area than BS alone, indicating accelerated graft degradation. Further studies on types of graft materials are required to verify the effect of EMD-liquid and to optimize its regenerative potential.

CLINICAL RELEVANCE

This study suggests that EMD-liquid may have beneficial effect on bone regeneration with synthetic bone substitute.

Red and Yellow Injectable Platelet-Rich Fibrin Demonstrated Differential Effects on Periodontal Ligament Stem Cell Proliferation, Migration, and Osteogenic Differentiation

The biological benefits of using two fractions derived from injectable platelet-rich fibrin (i-PRF) in bone regeneration remain unclear. Thus, the current study examined two fractionation protocols producing yellow i-PRF and red i-PRF on periodontal ligament stem cells (PDLSCs). The i-PRF samples from five donors were harvested from two different levels, with and without a buffy coat layer, to obtain red and yellow i-PRF, respectively. The PDLSCs were isolated and characterized before their experimental use. The culture medium in each assay was loaded with 20% of the conditioned medium containing the factors released from the red and yellow i-PRF. Cell proliferation and cell migration were determined with an MTT and trans-well assay, respectively. Osteogenic differentiation was investigated using alkaline phosphatase and Alizarin red staining. The efficiency of both i-PRFs was statistically compared. We found that the factors released from the red i-PRF had a greater effect on cell proliferation and cell migration. Moreover, the factors released from the yellow i-PRF stimulated PDLSC osteogenic differentiation earlier compared with the red i-PRF. These data suggest that the red i-PRF might be suitable for using in bone regeneration because it induced the mobilization and growth of bone regenerative cells without inducing premature mineralization.

Effect of the combined use of enamel matrix derivative and atelocollagen sponge scaffold on osteoblastic differentiation of mouse induced pluripotent stem cells in vitro

BACKGROUND AND OBJECTIVE

Induced pluripotent stem cells (iPSCs) are a candidate cell source in periodontal regenerative therapy. Enamel matrix derivative (EMD) has been shown to regenerate periodontal tissues, and atelocollagen sponge (ACS) is considered a suitable scaffold or carrier for growth factors. This study aimed to investigate the effect of combined use of EMD and an ACS scaffold on cell behaviors and differentiation of mouse iPSCs (miPSCs) in vitro.

MATERIAL AND METHODS

Following embryonic body formation from miPSCs, dissociated cells (miPS-EB-derived cells) were seeded onto ACS with or without EMD, and cultured in osteoblast differentiation medium. Scanning electron microscopy and histological analyses were used to assess cell morphology and infiltration within the ACS. Cell viability (metabolism) was determined using an MTS assay, and expression of mRNA of osteoblastic differentiation markers was assessed by quantitative RT -PCR. Alkaline phosphatase (ALP) staining intensity and activity were evaluated. Mineralization was assessed by von Kossa staining, and calcium content was quantitated using the methylxylenol blue method.

RESULTS

By 24 hours after seeding, miPS-EB-derived cells in both the EMD and control groups had attached to and infiltrated the ACS scaffold. Scanning electron microscopy images revealed that by day 14, many cytoplasmic protrusions and extracellular deposits, suggestive of calcified matrix, were present in the EMD group. There was a time-dependent increase in cell viability up to day 3, but no difference between groups was observed at any time point. The levels expressed of ALP and osterix genes were significantly higher in the EMD group than in the control group. Expression of runt-related transcription factor 2 was increased in the EMD group compared with the control group on day 7. EMD upregulated the expression of bone sialoprotein and osteopontin on day 14, whereas expression of osteocalcin was lower at all time points. The staining intensity and activity of ALP were higher in the EMD group than in the control group. Mineralization levels and calcium contents were significantly higher in the EMD group throughout the observation period.

CONCLUSION

These data suggest that combining ACS with EMD increases levels of osteoblastic differentiation and mineralization in miPS-EB-derived cells, compared with ACS used alone.

Healing of two-wall intra-bony defects treated with a novel EMD-liquid-A pre-clinical study in monkeys

AIM

To investigate the effect of a novel enamel matrix derivative formulation (EMD-liquid or Osteogain) combined with an absorbable collagen sponge (ACS) on periodontal wound healing in intra-bony defects in monkeys.

MATERIALS AND METHODS

Chronic two-wall intra-bony defects were created at the distal aspect of eight teeth in three monkeys (Macaca fascicularis). The 24 defects were randomly assigned to one of the following treatments: (i) open flap debridement (OFD) + ACS alone, (ii) OFD + Emdogain + ACS (Emdogain/ACS), (iii) OFD + Osteogain + ACS (Osteogain/ACS) or (iv) OFD alone. At 4 months, the animals were euthanized for histologic evaluation.

RESULTS

Osteogain/ACS resulted in more consistent formation of cementum, periodontal ligament and bone with limited epithelial proliferation compared to OFD alone, Emdogain/ACS and OFD + ACS. Among the four treatment groups, the Osteogain/ACS group demonstrated the highest amount of regenerated tissues. However, complete periodontal regeneration was not observed in any of the defects in the four groups.

CONCLUSIONS

The present findings indicate that in two-wall intra-bony defects, reconstructive surgery with Osteogain/ACS appears to be a promising novel approach for facilitating periodontal wound healing/regeneration, thus warranting further clinical testing.

Biofunctionalization of porcine-derived collagen matrix using enamel matrix derivative and platelet-rich fibrin: influence on mature endothelial cell characteristics in vitro

OBJECTIVES

The present study evaluated the effect of an enamel matrix derivative (EMD) and platelet-rich fibrin (PRF)-modified porcine-derived collagen matrix (PDCM) on human umbilical vein endothelial cells (HUVEC) in vitro.

MATERIALS AND METHODS

PDCM (mucoderm®) was prepared to 6 mm (±0.1 mm) diameter discs. PDCM samples were incubated with either EMD, PRF, or control solutions for 100 min at 4 °C before the experiments. Cell-inducing properties of test materials on HUVEC cells were tested with cell proliferation assays (MTT, PrestoBlue®), a cytotoxicity assay (ToxiLight®), a Boyden chamber migration assay, and a cell attachment assay. Scanning electron microscopy (SEM) imaging was performed to determine the surface and the architecture of the modified matrices.

RESULTS

Cell proliferation was elevated in the EMD and PRF groups compared with control (p each ≤0.046). PRF modification increased HUVEC migration ability by 8-fold compared with both control and EMD groups (p each <0.001). Both treatments significantly promoted the cell attachment of HUVEC to PDCM, as assessed by direct cell counts on the matrices (p each <0.001).

CONCLUSIONS

HUVEC cell characteristics were overall improved by EMD- and PRF- modified PDCM. Adsorbed bioactive molecules to the PDCM surface may have contributed to a more preferable environment to surrounding cells.

CLINICAL RELEVANCE

The results may give evidence that PDCM modification with EMD or PRF, respectively, might be a useful approach to improve clinical outcomes, to prevent inflammatory reactions and wound-healing disturbances, and to expand the clinical application area of PDCM.

Effects of platelet rich plasma (PRP) on human gingival fibroblast, osteoblast and periodontal ligament cell behaviour

BACKGROUND

The use of platelet rich plasma (PRP, GLO) has been used as an adjunct to various regenerative dental procedures. The aim of the present study was to characterize the influence of PRP on human gingival fibroblasts, periodontal ligament (PDL) cells and osteoblast cell behavior in vitro.

METHODS

Human gingival fibroblasts, PDL cells and osteoblasts were cultured with conditioned media from PRP and investigated for cell migration, proliferation and collagen1 (COL1) immunostaining. Furthermore, gingival fibroblasts were tested for genes encoding TGF-β, PDGF and COL1a whereas PDL cells and osteoblasts were additionally tested for alkaline phosphatase (ALP) activity, alizarin red staining and mRNA levels of osteoblast differentiation markers including Runx2, COL1a2, ALP and osteocalcin (OCN).

RESULTS

It was first found that PRP significantly increased cell migration of all cells up to 4 fold. Furthermore, PRP increased cell proliferation at 3 and 5 days of gingival fibroblasts, and at 3 days for PDL cells, whereas no effect was observed on osteoblasts. Gingival fibroblasts cultured with PRP increased TGF-β, PDGF-B and COL1 mRNA levels at 7 days and further increased over 3-fold COL1 staining at 14 days. PDL cells cultured with PRP increased Runx2 mRNA levels but significantly down-regulated OCN mRNA levels at 3 days. No differences in COL1 staining or ALP staining were observed in PDL cells. Furthermore, PRP decreased mineralization of PDL cells at 14 days post seeding as assessed by alizarin red staining. In osteoblasts, PRP increased COL1 staining at 14 days, increased COL1 and ALP at 3 days, as well as increased ALP staining at 14 days. No significant differences were observed for alizarin red staining of osteoblasts following culture with PRP.

CONCLUSIONS

The results demonstrate that PRP promoted gingival fibroblast migration, proliferation and mRNA expression of pro-wound healing molecules. While PRP induced PDL cells and osteoblast migration and proliferation, it tended to have little to no effect on osteoblast differentiation. Therefore, while the effects seem to favor soft tissue regeneration, the additional effects of PRP on hard tissue formation of PDL cells and osteoblasts could not be fully confirmed in the present in vitro culture system.