Angiogenic biomarkers and healing of living cellular constructs

Periostin in the relation between periodontal disease and atherosclerotic coronary artery disease: A pilot randomized clinical study

OBJECTIVE

The aim of this study was to analyze the effects of periodontal treatment on markers of atherosclerotic coronary artery disease and circulating levels of periostin.

BACKGROUND

Periostin is necessary for periodontal stability, but it is highly present in atherosclerotic plaques. Treatment of periodontal disease, with low levels of local periostin, is thought to reduce systemic levels of periostin. Thus, this may contribute to cardiovascular health.

METHODS

A pilot randomized controlled clinical trial was designed to include patients with severe periodontal disease and history of atherosclerotic coronary artery disease. Samples of gingival crevicular fluid (GCF) and serum were collected before and after periodontal treatment by periodontal surgery or non-surgical therapy. The levels of several markers of inflammation and cardiovascular damage were evaluated including CRP, IFN-γ, IL-1ß, IL-10, MIP-1α, periostin, and TNF-α in GCF and CRP, Fibrinogen, IFN-γ, IL-1ß, IL-6, IL-10, L-Selectin, MIP-1α, Periostin, TNF-α, and vWF in serum.

RESULTS

A total of 22 patients with an average of 56 years old were recruited for participating in this study. Twenty of them were male. Most of them (82%) had suffered an acute myocardial event and underwent surgery for placing 1, 2, or 3 stents in the coronary arteries more than 6 months ago but less than 1 year. The treatment of periodontal disease resulted in an overall improvement of all periodontal parameters. Regarding the evaluation of GCF and serum, a significant increase of periostin in the GCF was observed after periodontal surgery. In contrast, although other markers in GCF and serum improved, no significant correlations were found.

CONCLUSION

Treatment of periodontal disease through periodontal surgery induces a local and transient increase in the levels of periostin in the gingival crevicular fluid. The effects on systemic markers of inflammation and cardiovascular function have not been confirmed.

Effect of Intermittent Hypobaric Hypoxia Exposure on HIF-1α, VEGF, and Angiogenesis in the Healing Process of Post-Tooth Extraction Sockets in Rats

OBJECTIVE

 The aim of this study was to investigate the effect of intermittent hypobaric hypoxia (IHH) exposure on the expression of hypoxia-induced factor-1α (HIF-1α) messenger RNA (mRNA), vascular endothelial growth factor-a (VEGF-a) mRNA, and angiogenesis after tooth extraction in rats.

MATERIALS AND METHODS

 On 45 male Sprague-Dawley rats were performed the removal of the maxillary left first molar, and then they were randomly divided into 9 groups, namely: 4 groups that were exposed to IHH for 30 minutes every day in the Hypobaric Chamber at an altitude of 18,000 feet, with 1 time hypobaric hypoxia (HH), 3 times HH, 5 times HH, and 7 times HH; 4 normoxia groups that were terminated on days 1, 3, 5, and 7 after tooth extraction; and the 1 control group. Real-time polymerase chain reaction measured the molecular changes in the socket tissue after tooth extraction in rats to evaluate the expression of HIF-1α mRNA and VEGF mRNA. Histological changes with hematoxylin and eosin staining were noted to evaluate the amount of angiogenesis in the socket after tooth extraction. Molecular and histological parameters were calculated at the end of each experiment on days 0, 1, 3, 5, and 7 after tooth extraction, which exhibited the improvement phase of the wound-healing process.

RESULTS

 Increases in the expression of HIF-1α mRNA, VEGF mRNA, and angiogenesis were found in the IHH group compared with the normoxia group and the control group. The expression of HIF-1α mRNA increased significantly (p < 0.05) in the group after one time HH exposure on day 1, then decreased in the IHH group (three times HH exposure, five times HH exposure, and seven times HH exposure) approaching the control group. The expression of VEGF mRNA and angiogenesis began to increase after one time HH exposure on day 1, and increased again after three times HH exposure on day 3, then increased even more after five times HH exposure on day 5, and increased very significantly (**p < 0.05) after seven times HH exposure on day 7. It showed that repeated or intermittent exposure to HH conditions induced a protective response that made cells adapt under hypoxia conditions.

CONCLUSION

 IHH exposure accelerates the socket healing of post-tooth extraction, which is proven by changes in HIF-1α mRNA expression and increase in VEGF mRNA expression as stimuli for angiogenesis in post-tooth extraction sockets under hypobaric hypoxic condition, which also stimulates the formation of new blood vessels, thereby increasing blood supply and accelerating wound healing.

Evaluation of platelet derived growth factor-BB levels in injectable platelet rich fibrin coated graft using gingival pedicle split thickness tunnel technique for isolated gingival recession: A randomized controlled trial

Background

Use of injectable-platelet rich fibrin (i-PRF) in the field of periodontal regeneration is quite well known due to its efficacy. The study was aimed to evaluate the platelet derived growth factor-BB (PDGF-BB) levels in cases of isolated gingival recession using gingival pedicle split thickness tunnel technique (GPST) and de-epithelialized gingival graft (DGG) with or without coating it with i-PRF.

Methodology

20 patients exhibiting Miller's class I/II isolated gingival recession were selected for this parallel arm randomized controlled trial. Recipient site was prepared using GPST technique, free gingival graft was harvested and de-epithelialized, further graft was coated with i-PRF and wound fluid samples from surgical site were collected at baseline, 3rd day and 7th day for group A. The same procedure without coating the graft in i-PRF was carried out for group B. Clinical parameters like probing depth, recession depth, recession width, width of keratinized gingiva, wound healing index (WHI), complete root coverage was recorded at baseline and after 4 months.

Results

Significant intergroup difference was seen in WHI and the levels of PDGF-BB from baseline to the last estimated time point (p < 0.05).

Conclusion

The study emphasizes on the use of novel GPST technique in conjunction with DGG coated with liquid PRF, which has shown sustained release of PDGF-BB resulting in better wound healing.

The effect of smoking on clinical and biochemical early healing outcomes of coronally advanced flap with connective tissue graft: Prospective cohort study

BACKGROUND

This study aimed to determine the effects of smoking on early (≤3 months) clinical outcomes and relevant molecular biomarkers following root coverage surgery.

METHODS

Eighteen smokers and 18 nonsmokers, status biochemically verified, with RT1 gingival recession defects were recruited and completed study procedures. All patients received coronally advanced flap plus connective tissue graft. Baseline and 3 month recession depth (RD), recession width (RW), keratinized tissue width (KTW), clinical attachment level (CAL), and gingival phenotype (GP) were recorded. Root coverage (RC) percentage and complete root coverage (CRC) were calculated. Recipient (gingival crevicular fluid) and donor (wound fluid) site VEGF-A, HIF-1α, 8-OHdG, and ANG levels were determined.

RESULTS

There were no significant intergroup differences for any baseline or postoperative clinical parameters (P > 0.05), except for whole mouth gingival index (increased in nonsmokers at 3 months; P < 0.05). Compared to baseline, RD, RW, CAL, KTW, and GP significantly improved postoperatively, without significant intergroup differences. There were no significant intergroup differences for RC (smokers = 83%, nonsmokers = 91%, P = 0.069), CRC (smokers = 50%, nonsmokers = 72%, P = 0.177), and CAL gain (P = 0.193). The four biomarker levels significantly increased postoperatively (day 7; P ≤ 0.042) in both groups and returned to baseline (day 28) without significant intergroup differences (P > 0.05). Similarly, donor site parameters were not different between groups. Strong correlations, consistent over time, were found between biomarkers implicated in angiogenesis (VEGF-A, HIF-1α, and ANG).

CONCLUSIONS

The early (3 month) clinical and molecular changes after root coverage surgery utilizing a coronally advanced flap plus connective tissue graft are similar between smokers and nonsmokers.

Living cellular constructs for keratinized tissue augmentation: A 13-year follow-up from a split-mouth randomized, controlled, clinical trial

BACKGROUND

A 13-year follow-up was conducted of a short-term investigation of the use of living cellular construct (LCC) versus free gingival graft (FGG) for keratinized tissue width (KTW) augmentation in natural dentition, to evaluate the long-term outcomes and assess the changes occurring since the end of the original 6-month study.

METHODS

Twenty-four subjects out of the original 29 enrolled participants were available at the 13-year follow-up. The primary endpoint was the number of sites demonstrating stable clinical outcomes from 6 months to 13 years (defined as KTW gain, stability, or ≤0.5 mm of KTW loss, together with reduction, stability, or increase of probing depth, and recession depth [REC] ≤0.5 mm). Secondary outcomes included the assessment of KTW, attached gingiva width (AGW), REC, clinical attachment level, esthetics, and patient-reported outcomes at the 13-year visit, assessing the changes from baseline to 6 months.

RESULTS

Nine sites per group (42.9%) were found to have maintained stable (≤0.5 mm or improved) clinical outcomes from 6 months to 13 years. No significant differences were observed for the clinical parameters between LCC and FGG from 6 months to 13 years. However, the longitudinal mixed model analysis showed that FGG delivered significantly better clinical outcomes over 13 years (p < 0.01). LCC-treated sites exhibited superior esthetic outcomes compared to FGG-treated sites at 6 months and 13 years (p < 0.01). Patient-evaluated esthetics were significantly higher for LCC over FGG (p < 0.01). Patient overall treatment preference was also in favor of LCC (p < 0.01).

CONCLUSIONS

A similar stability of the treatment outcomes from 6 months to 13 years was found for LCC- and FGG-treated sites, with both approaches shown to be effective in augmenting KTW and AGW. However, superior clinical outcomes were found for FGG over 13 years, while LCC was associated with better esthetics and patient-reported outcomes than FGG.

Partial healing effects of St. John’s wort oil on the rat excisional wound model

Objective: St. John’s wort (SJW) oil (Hypericum perforatum) has been used for its immunomodulatory and anti-inflammatory effects. Several studies have shown the efficacy of SJW on wound healing. The aim of this study is to assess the effectiveness of SJW using a combination of biochemical, histopathological and laser Doppler evaluations. Materials and Methods: Sixteen young Wistar albino rats were used as case and control groups (having 8 in each group). After anesthesia protocol, 6 mm punch biopsy was taken from six separate sites on the rats’ dorsal skin. Three wounds were stitched (closed wounds); three wounds were left as they were (open wounds). SJW oil was administered topically to case group once a day for 14 days. Controls did not receive any treatment. Results: There was no statistical difference in blood perfusion between the groups. No statistical difference was present between the groups in GPx (glutathione peroxidase)values. Rat MDA (malonyldialdehyde) values were higher in the case group compared to the control group. SJW oil was found to be beneficial and effective within some histological parameters. Conclusion: SJW may be an effective salve within some parameters. Nevertheless, this judgment is uncertain due to the low sample size. We encourage further studies on this promising natural medicine.

Wound fluid sampling methods for proteomic studies: A scoping review

Understanding why some wounds are hard to heal is important for improving care and developing more effective treatments. The method of sample collection used is an integral step in the research process and thus may affect the results obtained. The primary objective of this study was to summarise and map the methods currently used to sample wound fluid for protein profiling and analysis. Eligible studies were those that used a sampling method to collect wound fluid from any human wound for analysis of proteins. A search for eligible studies was performed using MEDLINE, Embase and CINAHL Plus in May 2020. All references were screened for eligibility by one reviewer, followed by discussion and consensus with a second reviewer. Quantitative data were mapped and visualised using appropriate software and summarised via a narrative summary. After screening, 280 studies were included in this review. The most commonly used group of wound fluid collection methods were vacuum, drainage or use of other external devices, with surgical wounds being the most common sample source. Other frequently used collection methods were extraction from absorbent materials, collection beneath an occlusive dressing and direct collection of wound fluid. This scoping review highlights the variety of methods used for wound fluid collection. Many studies had small sample sizes and short sample collection periods; these weaknesses have hampered the discovery and validation of novel biomarkers. Future research should aim to assess the reproducibility and feasibility of sampling and analytical methods for use in larger longitudinal studies.

Effects of collagen membranes and bone substitute differ in periodontal ligament cell microtissues and monolayers

BACKGROUND

Barrier membranes and bone substitute are major tools of guided tissue regeneration (GTR) after periodontal disease. Integrity of the periodontal ligament plays a key role in periodontal health, but its functionality fails to be fully re-established by GTR after disease or trauma. Microtissue models suggest an in vivo-like model to develop novel GTR approaches due to its three-dimensionality. This study aims to assess the effects of collagen membranes and bone substitute on cell viability, adhesion and gene expression of regenerative and inflammatory biomarkers by periodontal ligament cell (PDLC) microtissues.

METHODS

Human PDLC microtissues and monolayers were cultured on collagen membranes or bone substitute. After 24 hours incubation, metabolic activity, focal adhesion, mRNA and protein production of collagen-type-I (COL1A1), periostin (POSTN), vascular endothelial growth factor (VEGF), angiogenin (ANG), interleukin (IL)6 and IL8 were measured by resazurin-based toxicity assay, focal adhesion staining, quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.

RESULTS

PDLC microtissues and monolayers were viable on collagen membranes and bone substitute, but microtissues were less metabolically active. Dominant staining of actin filaments was found in PDLC microtissues on collagen membranes. COL1A1, POSTN, VEGF, ANG and IL6 were modulated in PDLC microtissues on bone substitute, while there were no significant changes on collagen membranes. PDLC monolayers showed a different character of gene expression changes.

CONCLUSIONS

PDLC microtissues and monolayers react diversely to collagen membranes and bone substitute. Further descriptive and mechanistic tests will be required to clarify the potential of PDLC microtissues as in vivo-like model for GTR.

Crestal bone changes around early vs. conventionally loaded implants with a multi-phosphonate coated surface: A randomized pilot clinical trial

OBJECTIVES

To compare the marginal bone level around implants with a thin multi-phosphonate coated surface after either an early or conventional loading protocol.

MATERIAL AND METHODS

A randomized pilot clinical trial was conducted. Dental impressions were obtained after either 4 (test) or 8 weeks (control) and single crowns screwed-in 2 weeks later. Several variables were evaluated including radiographical marginal bone level (MBL), patient's level variables, and those related to the restoration and surrounding tissues. These data were obtained at several time points up to a 1-year follow-up.

RESULTS

Thirty-four patients were included in the study, 18 assigned to the test group. No differences at implant placement were detected for tissue thickness, keratinized mucosa, nor any other clinical or radiological variable. At the time of impressions, tissue was thinner in the test group (2.30 (0.46) versus 2.78 (0.66) mm, test versus control, respectively; p = .012) so shorter abutments were used in this group. Regardless, no significant changes in marginal bone level were detected neither within group along time nor between groups. The average MBL at the 1-year follow-up was -0.15 (0.32) versus -0.22 (0.37) (p = .443) (test versus control, respectively). None of the clinical or radiological variables evaluated had a determinant influence on the MBL at any visit nor group.

CONCLUSION

The use of implants with a multi-phosphonate coated surface for early loading offers successful radiographical outcomes 1 year after loading. MBL over time was not affected by taking the impressions 4 or 8 weeks after implant placement and loading them 2 weeks later.

Living cell-based regenerative medicine technologies for periodontal soft tissue augmentation

The cultivation of human living cells into scaffolding matrices has progressively gained popularity in the field of periodontal wound healing and regeneration. Living cellular constructs based on fibroblasts, keratinocytes alone or in combination have been developed and used as alternatives to autogenous soft tissue grafts in keratinized tissue augmentation and in root coverage procedures. Their promising advantages include reduced patient morbidity, unlimited graft availability, and comparable esthetics. This manuscript reviews soft tissue augmentation and root coverage procedures using bioengineered living cellular therapy and highlights their expected clinical, esthetic, and patient-related outcomes.

Blood flow kinetics of a xenogeneic collagen matrix following a vestibuloplasty procedure in the human gingiva-An explorative study

OBJECTIVES

The aim of the present study was to investigate temporal and spatial blood flow patterns following vestibuloplasty procedures using a collagen matrix (CM) to get an insight into the timing and direction of neovascularization in the CM.

METHODS

Five patients were treated using a modified apically repositioned flap combined with a CM. Intraoral photographs and blood flow measurements by laser speckle contrast imaging were taken for 12 months. Thirty regions of interest in the graft and the surrounding mucosa were evaluated. The clinical parameters were assessed after 6 and 12 months. VEGF expression was analyzed in the wound fluid on days 2 and 4.

RESULTS

At 6 months, the mean width of keratinized gingiva increased, but the thickness was unchanged. Scar formation was observed in all cases. Perfusion in the graft began to increase at the lateral and coronal edges and then spread concentrically toward the center. The apical side showed a significant delay in perfusion, the highest VEGF expression, and wound fluid production as well as the most abundant scar formation.

CONCLUSIONS

Neovascularization occurs mainly from the lateral and coronal edges, which may limit the extent of the surgical area. Abundant scar formation may be explained by increased VEGF expression induced by prolonged ischemia in this area.

CEMP-1 Levels in Periodontal Wound Fluid during the Early Phase of Healing: Prospective Clinical Trial

Objectives

Cementogenesis seems to be significantly compromised during tissue inflammation. In dental practice, surgical procedures are performed with the aim to regenerate periodontium including cementum. However, inflammation that occurs during the initial healing phases after surgery may impair regeneration of this tissues. The aim of the present study was to assess if surgical procedures designed to regenerate periodontium might affect levels of cementum protein-1 (CEMP-1) in periodontal wound fluid during early phase of healing.

Materials and Methods

In 36 patients, 18 intrabony periodontal defects were treated with regenerative therapy (REG group) and 18 suprabony periodontal defects were treated with open flap debridement (OFD group). In the experimental sites, gingival crevicular fluid was collected immediately before surgery, and periodontal wound fluid was collected 4, 7, 14, and 21 days after surgery. CEMP-1 levels were detected by indirect enzyme-linked immunosorbent assay technique.

Results

At the analysis, it resulted that there was a significant average difference in CEMP-1 values between the REG and OFD groups at baseline (p = 0.041), the CEMP-1-modeled average in the OFD group was lower by 0.45 ng/ml. There was a significant trend in CEMP-1 over time, and this trend was different among the 2 groups: the REG group showed a statistically significant rising CEMP-1 trend (0.18 ng/ml a week p = 0.012), while the OFD had a trend that was significantly lower (-0.22 ng/ml a week compared to the REG group trend p = 0.023), the OFD group lost on average 0.05 ng/ml a week. In REG sites, GCF protein levels resulted also related to clinical parameters.

Conclusions

During the initial inflammatory phase of periodontal healing, CEMP-1 levels decrease regardless of the surgical protocol applied. The surgical procedures used to regenerate periodontal tissue are able to reverse this trend and to induce significant increase of CEMP-1 in periodontal wound fluid after the first week postop.

Angiogenin production in response to hypoxia and l-mimosine in periodontal fibroblasts

BACKGROUND

A major mediator of angiogenesis is angiogenin, which is expressed in the early phase of healing in oral tissue engineering strategies. It is unclear how angiogenin is regulated in the periodontal tissue. The objective of this study was to reveal the regulation of angiogenin in response to hypoxia and the hypoxia mimetic agent l-mimosine in periodontal fibroblasts.

METHODS

Human fibroblasts of the periodontal ligament (PDLF) and the gingiva (GF) in monolayer and spheroid cultures were exposed to hypoxia or l-mimosine. The production of angiogenin was evaluated at mRNA and protein levels with reverse transcription quantitative polymerase chain reaction and enzyme-linked immunosorbent assays, respectively. Echinomycin, an inhibitor of hypoxia-inducible factor (HIF)-1 activity, was used to test the involvement of HIF-1.

RESULTS

Our data show that hypoxia and l-mimosine can increase angiogenin mRNA and protein levels in PDLF monolayer cultures. In GF monolayer cultures, we found an increase of angiogenin at the mRNA level in response to hypoxia. The increase of angiogenin can be blocked by inhibition of HIF-1 signaling via echinomycin. In PDLF and GF spheroid cultures, the impact of hypoxia and l-mimosine did not reach the level of significance.

CONCLUSION

Hypoxia and the hypoxia mimetic agent l-mimosine can increase the production of angiogenin via HIF-1 signaling in PDLF monolayer cultures but not in spheroid cultures. GF were less sensitive to the impact of hypoxia and l-mimosine. Overall, these results suggest a link between hypoxia, HIF-1 signaling and angiogenin in the periodontium.

Evaluation of the Effect of Topical Hypericum perforatum Oil on Excisional Palatal Wound Healing in Rabbits

Aim: The aim of this study was to evaluate the effect of Hypericum perforatum (HP) oil on wound-healing process in rabbit palatal mucosa. Materials and Methods: Thirty-six New Zealand albino rabbits were randomly allocated to following groups; (1) HP oil (test, n = 18) and (2) olive oil (control, n = 18). Palatinal excisional wounds were created and the oils were topically applied (0.1 ml, 30 s, twice a day). Gingival biopsies were excised, and analyzed for re-epithelialization (RE) and granulation tissue maturation (GTM) on days 3, 7, and 14 after surgery. Levels of vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF-2) were assessed using the immunohistochemical method. Apoptotic cells (ACs) were evaluated using TUNEL staining. Enzyme-linked immunosorbent assay was used to assess tissue catalase (CAT) and malondialdehyde (MDA) levels. Results: RE and GTM were completed earlier in the HP oil group than in the control group. The number of positively stained cells/vessels was higher in olive oil than in the test group on day 3 for FGF-2 and on days 3 and 7 for VEGF (p < 0.05). In contrast, on day 14, a higher number of vessels was observed in the HP oil group than in the control group. HP oil treatment reduced the number of ACs compared to olive oil (p < 0.05), but the difference during the healing period did not reach significance. Tissue CAT and MDA levels between groups were not different, and also the results were the same when the levels were analyzed by the evaluated time periods (p > 0.05). Conclusions: The results of this study demonstrated that topical HP oil treatment did not provide an additional benefit to its base, olive oil, in the early phase of secondary wound healing.

Comparison of Attachment and Proliferation of Human Gingival Fibroblasts on Different Collagen Membranes

Background and Aim

Human gingival fibroblasts cultured on collagen membrane as an alternative treatment method used in tissue regeneration can lead to improved results in root coverage. The aim of this study was to evaluate the human gingival fibroblast proliferation and adhesion cultured on three types of collagen membranes.

Materials and Methods

In this in vitro study, first-line human gingival fibroblast cells (HGF1-RT1) prepared and cultured on three membranes, including porcine pericardium (PP) (Jason, Botiss dental), human pericardium (HP) (Regen, Faravardeh Baft Iranian), and glutaraldehyde cross-linked (GC) (BioMend Extend, Zimmer Dental). Cell survival was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) after 24, 48, and 72 h and 7 days. Furthermore, morphology and adhesion of cells on the membrane were evaluated after 1 and 7 days by electron microscopy (scanning electron microscopy [SEM]). Statistical analysis was performed using two-way ANOVA with a significance level of 0.05.

Results

Based on the results of MTT, cell survival on HP and PP membranes after 7 days significantly increased (P < 0.001), but for the GC membrane, it was reduced after 7 days (P = 0.031). Cell survival on HP and PP membranes did not differ (P = 1) and was more than GC (P < 0.001). SEM images showed that the adhesion of cells was better on HP and PP membranes than GC.

Conclusion

The results of this study showed that natural collagen membranes (HP and PP) similarly support proliferation and adhesion of gingival fibroblasts. Survival and adhesion of gingival fibroblasts on cross-linked collagen membrane was less than two other membranes.

L-mimosine and hypoxia can increase angiogenin production in dental pulp-derived cells

Background

Angiogenin is a key molecule in the healing process which has been successfully applied in the field of regenerative medicine. The role of angiogenin in dental pulp regeneration is unclear. Here we aimed to reveal the impact of the hypoxia mimetic agent L-mimosine (L-MIM) and hypoxia on angiogenin in the dental pulp.

Methods

Human dental pulp-derived cells (DPC) were cultured in monolayer and spheroid cultures and treated with L-MIM or hypoxia. In addition, tooth slice organ cultures were applied to mimic the pulp-dentin complex. We measured angiogenin mRNA and protein levels using qPCR and ELISA, respectively. Inhibitor studies with echinomycin were performed to reveal the role of hypoxia-inducible factor (HIF)-1 signaling.

Results

Both, L-MIM and hypoxia increased the production of angiogenin at the protein level in monolayer cultures of DPC, while the increase at the mRNA level did not reach the level of significance. The increase of angiogenin in response to treatment with L-MIM or hypoxia was reduced by echinomycin. In spheroid cultures, L-MIM increased angiogenin at protein levels while the effect of hypoxia was not significant. Angiogenin was also expressed and released in tooth slice organ cultures under normoxic and hypoxic conditions and in the presence of L-MIM.

Conclusions

L-MIM and hypoxia modulate production of angiogenin via HIF-1 differentially and the response depends on the culture model. Given the role of angiogenin in regeneration the here presented results are of high relevance for pre-conditioning approaches for cell therapy and tissue engineering in the field of regenerative endodontics.

Soft tissue substitutes in non-root coverage procedures: a systematic review and meta-analysis

OBJECTIVES

The present systematic review compared the effectiveness of soft tissue substitutes (STSs) and autogenous free gingival grafts (FGGs) in non-root-coverage procedures to increase keratinized tissue (KT) width around teeth.

MATERIALS AND METHODS

Included studies fulfilled the following main eligibility criteria: (a) preclinical in vivo or human controlled trials using FGG as control, (b) non-root-coverage procedures, and (c) assessment of KT width. Meta-analysis was performed on the gain in KT width (primary outcome variable) and several secondary variables.

RESULTS

Eight human trials with short observation time evaluating five different STSs were identified. FGG yielded consistently significantly (p < 0.001) larger increase in KT width irrespective whether the comparison regarded an acellular matrix or a tissue-engineered STS. Further, FGG yielded consistently ≥2 mm KT width postoperatively, while use of STS did not, in the few studies reporting on this outcome. On the other hand, STSs resulted in significantly better aesthetic outcomes and received greater patient preference (p < 0.001).

CONCLUSIONS

Based on relatively limited evidence, in non-root-coverage procedures, FGG (1) resulted consistently in significantly larger increase in KT width compared to STS and (2) yielded consistently ≥2 mm KT width postoperatively, while STSs did not. STSs yielded significantly better aesthetic outcomes, received greater patient preference, and appeared safe.

CLINICAL RELEVANCE

Larger and more predictable increase in KT width is achieved with FGG, but STSs may be considered when aesthetics is important. Clinical studies reporting relevant posttreatment outcomes, e.g., postop KT width ≥2 mm, on the long-term (>6 months) are warranted.

Emerging regenerative approaches for periodontal reconstruction: a systematic review from the AAP Regeneration Workshop

More than 30 years have passed since the first successful application of regenerative therapy for treatment of periodontal diseases. Despite being feasible, periodontal regeneration still faces numerous challenges, and complete restoration of structure and function of the diseased periodontium is often considered an unpredictable task. This review highlights developing basic science and technologies for potential application to achieve reconstruction of the periodontium. A comprehensive search of the electronic bibliographic database PubMed was conducted to identify different emerging therapeutic approaches reported to influence either biologic pathways and/or tissues involved in periodontal regeneration. Each citation was assessed based on its abstract, and the full text of potentially eligible reports was retrieved. Based on the review of the full papers, their suitability for inclusion in this report was determined. In principle, only reports from scientifically well-designed studies that presented preclinical in vivo (animal studies) or clinical (human studies) evidence for successful periodontal regeneration were included. Hence, in vitro studies, namely those conducted in laboratories without any live animals, were excluded. In case of especially recent and relevant reviews with a narrow focus on specific regenerative approaches, they were identified as such, and thereby the option of referring to them to summarize the status of a specific approach, in addition to or instead of listing each separately, was preserved. Admittedly, the presence of subjectivity in the selection of studies to include in this overview cannot be excluded. However, it is believed that the contemporary approaches described in this review collectively represent the current efforts that have reported preclinical or clinical methods to successfully enhance regeneration of the periodontium. Today's challenges facing periodontal regenerative therapy continue to stimulate important research and clinical development, which, in turn, shapes the current concept of periodontal tissue engineering. Emerging technologies--such as stem cell therapy, bone anabolic agents, genetic approaches, and nanomaterials--also offer unique opportunities to enhance the predictability of current regenerative surgical approaches and inspire development of novel treatment strategies.

Periodontal Soft Tissue Non-Root Coverage Procedures: Practical Applications From the AAP Regeneration Workshop

Focused Clinical Question: What are the indications and clinical applications for gingival augmentation procedures, and what factors guide the choice among treatment options in specific situations? Summary: Although there is still controversy regarding whether there needs to be a minimum amount of attached gingiva to maintain the stability of the gingival margin, prospective and retrospective studies have shown that, in the presence of suboptimal plaque control and clinical inflammation, attachment loss and gingival recession (GR) may result unless a minimum amount of keratinized tissue (KT) and attached gingiva are present. Treatment of mucogingival deformities requires gingival augmentation procedures that address both a functional and esthetic component for the patient. Although free gingival grafts (FGGs) are considered the gold standard for treatment of GR defects to obtain root coverage, augmentation of KT and attached gingiva may be accomplished by FGG or other autogenous grafting options, including the free connective tissue graft, the lateral pedicle graft, and the double papilla technique. In addition, the modified apically repositioned flap can be considered in some instances. Alternatives to autogenous graft tissue include acellular dermal matrix, extracellular matrix membrane, bilayer collagen matrix, and living cellular construct. Conclusions: Understanding the clinical importance of the presence of a minimum amount of attached gingiva in patients with suboptimal hygiene is an important first step in addressing the condition. Patient education to address plaque control and counseling to quit smoking in patients who are smokers help enhance the success of these mucogingival surgical procedures. An analysis of patient-specific factors will help with the appropriate choice of surgical procedures aimed at augmenting the dimension of KT/attached gingival tissue. Evidence supporting the treatment decisions described in this practical application is summarized in the companion papers from the American Academy of Periodontology Regeneration Workshop (Kim and Neiva, J Periodontol 2015;86(Suppl.):S56-S72; Scheyer et al., J Periodontol 2015;86(Suppl.):S73-S76).

Effect of living cellular sheets on the angiogenic potential of human microvascular endothelial cells

BACKGROUND

A fundamental issue limiting the efficacy of surgical approaches designed to correct periodontal mucogingival defects is that new tissues rely on limited sources of blood supply from the adjacent recipient bed. Accordingly, therapies based on tissue engineering that leverage local self-healing potential may represent promising alternatives for the treatment of mucogingival defects by inducing local vascularization. The aim of this study is to evaluate the effect of commercially available living cellular sheets (LCS) on the angiogenic potential of neonatal dermal human microvascular endothelial cells (HMVEC-dNeo).

METHODS

The effect of LCS on HMVEC-dNeo proliferation, migration, capillary tube formation, gene expression, and production of angiogenic factors was evaluated over time.

RESULTS

LCS positively influenced HMVEC-dNeo proliferation and migration. Moreover, HMVEC-dNeo incubated with LCS showed transcriptional profiles different from those of untreated cells. Whereas increased expression of angiogenic genes predominated early on in response to LCS, late-phase responses were characterized by up- and downregulation of angiostatic and angiogenic genes. However, this trend was not confirmed at the protein level, as LCS induced increased production of most of the angiogenic factors tested (i.e., epidermal growth factor [EGF], heparin-binding EGF-like growth factor, interleukin 6, angiopoietin, platelet-derived growth factor-BB, placental growth factor, and vascular endothelial growth factor) throughout the investigational period. Finally, although LCS induced HMVEC-dNeo proliferation, migration, and expression of angiogenic factors, additional factors and environmental pressures are likely to be required to promote the development of complex, mesh-like vascular structures.

CONCLUSION

LCS favor initial mechanisms that govern angiogenesis but failed to enhance or accelerate HMVEC-dNeo morphologic transition to complex vascular structures.

Biochemical indicators of implantation success of tissue-engineered oral mucosa

Real-time (RT) determination of the health of in vitro tissue-engineered constructs prior to grafting is essential for prediction of success of the implanted tissue-engineered graft. In addition, the US Food and Drug Administration requires specific release criteria in RT prior to the release of tissue-engineered devices for human use. In principle, assessing the viability and functionality of the cellular component can be achieved by quantifying the secretion of growth factors and chemokines of tissue-engineered constructs. Ex vivo-produced oral mucosa equivalents (EVPOMEs) were fabricated under thermally stressed conditions at 43 °C for 24 h to create a functionally compromised EVPOME. We used microchannel enzyme-linked immunosorbent assay to evaluate the functionality of the cellular component, oral keratinocytes, of stressed and unstressed EVPOMEs by measuring the release of vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), human β-defensin 1 (hBD-1), and tissue inhibitor of metalloproteinase 1 and 2 (TIMP-1 and -2) into the spent medium, which was collected on the same day prior to graft implantation into severe combined immunodeficiency mice. Implanted EVPOMEs' histology on the seventh postimplantation day was used to correlate outcomes of grafting to secreted amounts of IL-8, hBD-1, VEGF, TIMP-1, and TIMP-2 from corresponding EVPOMEs. Our findings showed that significantly higher levels of IL-8, hBD-1, and TIMP-2 were secreted from controls than from thermally stressed EVPOMEs. We also found a direct correlation between secreted VEGF and IL-8 and blood vessel counts of implanted EVPOMEs. We concluded that measuring the constitutive release of these factors can be used as noninvasive predictors of healthy tissue-engineered EVPOMEs in RT, prior to their implantation.

Experimental orthotopic transplantation of a tissue-engineered oesophagus in rats

A tissue-engineered oesophageal scaffold could be very useful for the treatment of pediatric and adult patients with benign or malignant diseases such as carcinomas, trauma or congenital malformations. Here we decellularize rat oesophagi inside a perfusion bioreactor to create biocompatible biological rat scaffolds that mimic native architecture, resist mechanical stress and induce angiogenesis. Seeded allogeneic mesenchymal stromal cells spontaneously differentiate (proven by gene-, protein and functional evaluations) into epithelial- and muscle-like cells. The reseeded scaffolds are used to orthotopically replace the entire cervical oesophagus in immunocompetent rats. All animals survive the 14-day study period, with patent and functional grafts, and gain significantly more weight than sham-operated animals. Explanted grafts show regeneration of all the major cell and tissue components of the oesophagus including functional epithelium, muscle fibres, nerves and vasculature. We consider the presented tissue-engineered oesophageal scaffolds a significant step towards the clinical application of bioengineered oesophagi.

Real-time quantification of proteins secreted by artificial connective tissue made from uni- or multidirectional collagen I scaffolds and oral mucosa fibroblasts

Previously, we found that oral autologous artificial connective tissue (AACT) had a different protein secretion profile to that of clot-embedded AACT. Other oral mucosa substitutes, having different cell types and scaffolds, had dissimilar secretion profiles of proteins (including that for AACT) that influence healing outcome; thus, to ascertain the profiles of factors secreted by artificial tissue and whether they are influenced by their microstructure might help in understanding their bioactivity. An important component of tissue microstructure is the fiber orientation of the scaffold used for manufacturing it. This work developed a surface plasmon resonance (SPR) methodology to quantify factors secreted by oral artificial connective tissue (ACT) in culture medium, and a method to manufacture unidirectional laminar collagen I scaffolds. The SPR methodology was used for assessing differences in the protein secretion profile of ACT made with collagen scaffolds having different fiber orientation (unidirectional vs multidirectional). Oral fibroblasts seeded onto unidirectional scaffolds increased the secretion of six factors involved in modulating healing compared to those seeded onto multidirectional scaffolds. Histological analysis of uni- and multidirectional ACT showed that cells differ in their alignment and morphology. This SPR-methodology led to nanoscale detection of paracrine factors and might be useful to study biomarkers of three-dimensional cell growth, cell differentiation, and wound-healing progression.

Application of Platelet-Rich Plasma to Disorders of the Knee Joint

IMPORTANCE

The promising therapeutic potential and regenerative properties of platelet-rich plasma (PRP) have rapidly led to its widespread clinical use in musculoskeletal injury and disease. Although the basic scientific rationale surrounding PRP products is compelling, the clinical application has outpaced the research.

OBJECTIVE

The purpose of this article is to examine the current concepts around the basic science of PRP application, different preparation systems, and clinical application of PRP in disorders in the knee.

EVIDENCE ACQUISITION

A systematic search of PubMed for studies that evaluated the basic science, preparation and clinical application of platelet concentrates was performed. The search used terms, including platelet-rich plasma or PRP preparation, activation, use in the knee, cartilage, ligament, and meniscus. Studies found in the initial search and related studies were reviewed.

RESULTS

A comprehensive review of the literature supports the potential use of PRP both nonoperatively and intraoperatively, but highlights the absence of large clinical studies and the lack of standardization between method, product, and clinical efficacy. Conclusions and Relevance. In addition to the call for more randomized, controlled clinical studies to assess the clinical effect of PRP, at this point, it is necessary to investigate PRP product composition and eventually have the ability to tailor the therapeutic product for specific indications.

Attachment, proliferation and collagen type I mRNA expression of human gingival fibroblasts on different biodegradable membranes

The purpose of this study was to investigate adhesion, proliferation and type I collagen (COL I) mRNA expression of gingival fibroblasts on different membranes used in periodontal applications. Collagen (C), acellular dermal matrix (ADM) and polylactic acid; polyglycolic acid; lactide/glycolide copolymer (PLGA) biodegradable membranes were combined with gingival fibroblasts in culture and incubated for 48 h. Cell adhesion was examined with scanning electron and confocal microscopy. MTT assay was used to measure proliferation. COL I mRNA expression was assessed using quantitative-polymerase chain reaction (QPCR). The PLGA group exhibited the lowest cell survival on day 5 and 10, and lowest cell proliferation on days 5, 10 and 14. While cell proliferation was similar in C and ADM groups, the C membrane showed a slightly greater increase in viable cells to day 10. Confocal and scanning electron microscopy confirmed the results of proliferation and MTT assays. The highest COL I mRNA expression was noted in the PLGA membrane group when compared to the C (p < 0.01) and ADM (p < 0.05) membrane groups. These data revealed that adherence and proliferation of primary gingival fibroblasts on collagen-based C and ADM membranes is better than that seen with PLGA membranes, and thus may be preferable in the treatment of gingival recession defects.

Salivary diagnostics for periodontal diseases

BACKGROUND

and Overview The use of salivary diagnostics continues to develop and advance the field of risk determination for periodontal diseases. Researchers are investigating genetic, microbial and protein biomarkers with the objective of translating findings to such aspects of clinical care as broad patient screening, monitoring and treatment planning.

METHODS

/st> In this review, the author briefly explores currently available salivary diagnostics used to identify bacteria prevalent in periodontal disease, and focuses on the future development and use of a variety of rapid disease detection platforms, such as lab-on-a-chip, as a point-of-care device for identification of patients' risk.

CONCLUSIONS

and

CLINICAL IMPLICATIONS

/st> Several diagnostic tests are commercially available, and point-of-care tests are under development. However, challenges remain regarding the introduction of these technologies to clinical practice and adoption by dental practitioners for promotion of personalized oral health care.

Bone repair cells for craniofacial regeneration

Reconstruction of complex craniofacial deformities is a clinical challenge in situations of injury, congenital defects or disease. The use of cell-based therapies represents one of the most advanced methods for enhancing the regenerative response for craniofacial wound healing. Both somatic and stem cells have been adopted in the treatment of complex osseous defects and advances have been made in finding the most adequate scaffold for the delivery of cell therapies in human regenerative medicine. As an example of such approaches for clinical application for craniofacial regeneration, Ixmyelocel-T or bone repair cells are a source of bone marrow derived stem and progenitor cells. They are produced through the use of single pass perfusion bioreactors for CD90+ mesenchymal stem cells and CD14+ monocyte/macrophage progenitor cells. The application of ixmyelocel-T has shown potential in the regeneration of muscular, vascular, nervous and osseous tissue. The purpose of this manuscript is to highlight cell therapies used to repair bony and soft tissue defects in the oral and craniofacial complex. The field at this point remains at an early stage, however this review will provide insights into the progress being made using cell therapies for eventual development into clinical practice.

Translational and clinical applications of salivary diagnostics

There have been significant advances in techniques for the detection of biomarker signals in the oral cavity (e.g., ELISAs for proteins, PCR for RNA and DNA) as well as the engineering and development of microfluidic approaches to make oral-based point-of-care (POC) methods for the diagnosis for both local and systemic conditions a reality. In this section, we focus on three such approaches, namely, periodontal disease management, early markers for systemic diseases, and salivary markers useful for pharmacogenomic studies. Novel approaches using non-invasive, salivary samples and user-friendly devices offer results that are as sensitive and specific as laboratory-based analyses using blood or urine.

Future Prospects for Periodontal Bioengineering Using Growth Factors

Polypeptide growth factors have demonstrated strong potential to repair defects associated with teeth and dental implants. Over the past two decades, intense research efforts have led to the clinical development of several growth factors or biologic agents, including bone morphogenetic proteins, platelet-derived growth factor, fibroblast growth factors, and enamel matrix proteins. Several of these growth factors are now being used clinically for a variety of applications, such as the promotion of periodontal regeneration, sinus floor augmentation, and root coverage procedures. Although clinical results have been promising and growth factors add another dimension to clinical care, optimization of growth factor targeting approaches to periodontal wounds remains a challenge. Enhancement of growth factor local application to improve bioavailability, bioactivity, and allowance of three-dimensional reconstruction of complex anatomic defects is a goal. This article will highlight developments for growth factor delivery to better stimulate the wound healing response for periodontal and bone regeneration in the maxillofacial region.

Cell- and gene-based therapeutic strategies for periodontal regenerative medicine

Inflammatory periodontal diseases are a leading cause of tooth loss and are linked to multiple systemic conditions, such as cardiovascular disease and stroke. Reconstruction of the support and function of affected tooth-supporting tissues represents an important therapeutic endpoint for periodontal regenerative medicine. An improved understanding of periodontal biology coupled with current advances in scaffolding matrices has introduced novel treatments that use cell and gene therapy to enhance periodontal tissue reconstruction and its biomechanical integration. Cell and gene delivery technologies have the potential to overcome limitations associated with existing periodontal therapies, and may provide a new direction in sustainable inflammation control and more predictable tissue regeneration of supporting alveolar bone, periodontal ligament, and cementum. This review provides clinicians with the current status of these early-stage and emerging cell- and gene-based therapeutics in periodontal regenerative medicine, and introduces their future application in clinical periodontal treatment. The paper concludes with prospects on the application of cell and gene tissue engineering technologies for reconstructive periodontology.