The effects of tetracycline-loaded silk fibroin membrane on proliferation and osteogenic potential of mesenchymal stem cells

Hybrid system with stable structure of hard/soft tissue substitutes induces re-osseointegration in a rat model of biofilm-mediated peri-implantitis

Re-osseointegration of an infected/contaminated dental implant poses major clinical challenges. We tested the hypothesis that the application of an antibiotic-releasing construct, combined with hard/soft tissue replacement, increases the efficacy of reconstructive therapy. We initially fabricated semi-flexible hybrid constructs of β-TCP/PHBHHx, with tetracycline (TC) (TC amounts: 5%, 10%, and 15%). Thereafter, using in vitro assays, TC release profile, attachment to rat bone marrow-derived stem cells (rBMSCs) and their viability as well as anti-bacterial activity were determined. Thereafter, regenerative efficacies of the three hybrid constructs were assessed in a rat model of peri-implantitis induced by Aggregatibacter actinomycetemcomitans biofilm; control animals received β-TCP/Bio-Gide and TC injection. Eight weeks later, maxillae were obtained for radiological, histological, and histomorphometric analyses of peri-implant tissues. Sulcus bleeding index was chronologically recorded. Serum cytokines levels of IL-6 and IL-1β were also evaluated by enzyme-linked immunosorbent assay. Substantial amounts of tetracycline, from hybrid constructs, were released for 2 weeks. The medium containing the released tetracycline did not affect the adhesion or viability of rBMSCs; however, it inhibited the proliferation of A. actinomycetemcomitans. Osteogenesis and osseointegration were more marked for the 15% hybrid construct group than the other two groups. The height of attachment and infiltration of inflammatory cells within fibrous tissue was significantly reduced in the experimental groups than the control group. Our protocol resulted in re-osseointegration on a biofilm-contaminated implant. Thus, an antibiotic releasing inorganic/organic construct may offer a therapeutic option to suppress infection and promote guided tissue regeneration thereby serving as an integrated multi-layer substitute for both hard/soft tissues.

Antibiotic-Loaded Polymeric Barrier Membranes for Guided Bone/Tissue Regeneration: A Mini-Review

Polymeric membranes are frequently used for bone regeneration in oral and periodontal surgery. Polymers provide adequate mechanical properties (i.e., Young’s modulus) to support oral function and also pose some porosity with interconnectivity to permit for cell proliferation and migration. Bacterial contamination of the membrane is an event that may lead to infection at the bone site, hindering the clinical outcomes of the regeneration procedure. Therefore, polymeric membranes have been proposed as carriers for local antibiotic therapy. A literature search was performed for papers, including peer-reviewed publications. Among the different membranes, collagen is the most employed biomaterial. Collagen membranes and expanded polytetrafluoroethylene loaded with tetracyclines, and polycaprolactone with metronidazole are the combinations that have been assayed the most. Antibiotic liberation is produced in two phases. A first burst release is sometimes followed by a sustained liberation lasting from 7 to 28 days. All tested combinations of membranes and antibiotics provoke an antibacterial effect, but most of the time, they were measured against single bacteria cultures and usually non-specific pathogenic bacteria were employed, limiting the clinical relevance of the attained results. The majority of the studies on animal models state a beneficial effect of these antibiotic functionalized membranes, but human clinical assays are scarce and controversial.

An Insight into Nano Silver Fluoride-Coated Silk Fibroin Bioinspired Membrane Properties for Guided Tissue Regeneration

The current work focuses on the development of a novel electrospun silk fibroin (SF) nonwoven mat as a GTR membrane with antibacterial, biomineralization and biocompatible properties. The γ-poly glutamic acid (γ-PGA)-capped nano silver fluoride (NSF) and silver diamine fluoride (SDF) were first synthesized, which were dip-coated onto electrospun silk fibroin mats (NSF-SF and SDF-SF). UV-Vis spectroscopy and TEM depicted the formation of silver nanoparticles. NSF-SF and SDF-SF demonstrated antibacterial properties (against Porphyromonas gingivalis) with 3.1 and 6.7 folds higher relative to SF, respectively. Post-mineralization in simulated body fluid, the NSF-SF effectively promoted apatite precipitation (Ca/P ~1.67), while the SDF-SF depicted deposition of silver nanoparticles, assessed by SEM-EDS. According to the FTIR-ATR deconvolution analysis, NSF-SF portrayed ~75% estimated hydroxyapatite crystallinity index (CI), whereas pure SF and SDF-SF demonstrated ~60%. The biocompatibility of NSF-SF was ~82% when compared to the control, while SDF-coated samples revealed in vitro cytotoxicity, further needing in vivo studies for a definite conclusion. Furthermore, the NSF-SF revealed the highest tensile strength of 0.32 N/mm and 1.76% elongation at break. Therefore, it is substantiated that the novel bioactive and antibacterial NSF-SF membranes can serve as a potential candidate, shedding light on further in-depth analysis for GTR applications.

The Gingiva from the Tissue Surrounding the Bone to the Tissue Regenerating the Bone: A Systematic Review of the Osteogenic Capacity of Gingival Mesenchymal Stem Cells in Preclinical Studies

The current review aims to systematically assess the osteogenic capacity of gingiva-derived mesenchymal stem cells (GMSCs) in preclinical studies. A comprehensive electronic search of PubMed, Embase, Web of Science, and Scopus databases, as well as a manual search of relevant references, was performed in June 2020 without date or language restrictions. Eligibility criteria were the following: studies that compared mesenchymal stem cells (MSCs) derived from the gingiva with other MSC sources (in vitro or in vivo) or cell-free scaffold (in vivo) and studies that reported at least one of the following outcomes: osteogenic potential and new bone formation for in vitro and in vivo, respectively. Moreover, the assessment of included studies was conducted using appropriate guidelines. From 646 initial retrieved studies, 35 full-text articles were subjected to further screening and 26 studies were selected (20 in vitro studies and 6 in vivo studies). GMSCs showed great proliferation capacity and expressed recognized mesenchymal stem cell markers, particularly CD90. In vitro, MSC sources including GMSCs were capable of undergoing osteogenic differentiation with less ability in GMSCs, while most in vivo studies confirmed the capacity of GMSCs to regenerate bony defects. Concerning the assessment of methodological quality, in vitro studies met the relevant guideline except in five areas: the sample size calculation, randomization, allocation concealment, implementation, and blinding, and in vivo publications had probably low risk of bias in most domains except in three areas: allocation concealment, attrition, and blinding items.

Dimethyl Sulfoxide Leads to Decreased Osteogenic Differentiation of Stem Cells Derived from Gingiva via Runx2 and Collagen I Expression

Objectives Dimethyl sulfoxide (DMSO) plays various functions, including cellular functions such as cellular growth. The aim of this study was to evaluate the effects of DMSO on the proliferation and osteogenic differentiation of human gingiva-derived stem cells.

Materials and Methods Stem cells derived from gingiva were cultured in the presence of DMSO at concentrations ranging from 0.01 to 10%.

Statistical Analysis We performed a one-way analysis of variance (ANOVA) with post hoc test to determine the differences between the groups using a commercially available program and the level of significance was 0.05.

Results The cells in the control group showed normal fibroblast morphology. The cells treated with 0.01%, 0.01%, 0.1%, and 1% DMSO were morphologically similar to those from the control group on each day. Statistically significant decreases in cell counting kit-8 (CCK-8) values were seen in the 3% and 10% DMSO groups ( p < 0.05). A statistically significant decrease in alkaline phosphatase activity was seen in the 3% DMSO group. ( p < 0.05). The application of DMSO produced a decrease in alizarin red S staining. The expression of Runx2 and collagen I by immunofluorescence decreased as the dose of lovastatin increased.

Conclusion The effects of DMSO on the viability of osteogenic differentiation among stem cells derived from human gingiva were evaluated. Applying DMSO produced decreased cell viability and decreased osteogenic differentiation in this experimental setting. This should be considered when designing and interpreting the data, and a DMSO-free method may be considered for bone regeneration applications.

A Study of the Effects of Doxorubicin-Containing Liposomes on Osteogenesis of 3D Stem Cell Spheroids Derived from Gingiva

The objective of the present investigation is to determine the effects of neutral, anionic, and cationic liposomes loaded with doxorubicin with thin-lipid-film-hydration method on the cellular viability and osteogenesis of stem cell spheroids. Spheroid formation and morphology of the three-dimensional spheroid were noted with an inverted microscope. Quantitative cellular viability was assessed using a commercially available kit. Osteogenic potential was evaluated by applying alkaline phosphatase activity and anthraquinone dye of Alizarin Red S. Western blot analysis was performed using collagen I expression. Spheroids were formed in each silicon elastomer-based concave microwell on Day 1. Noticeable changes of the spheroid were seen with a higher concentration of doxorubicin, especially in the cationic liposome group at Days 5 and 7. We found that the application of doxorubicin for 5 days significantly reduced the cellular viability. A higher concentration of doxorubicin produced a significant decrease in alkaline phosphatase activity. Alizarin Red S staining showed that extracellular calcium deposits were evenly noted in each group. An increase of calcium deposits was noted on Day 14 when compared to Day 7. The morphology of the groups with higher concentrations of doxorubicin showed to be more dispersed. We noticed that doxorubicin-loaded cationic liposomes resulted in the highest uptake of the examined cell spheroids and that doxorubicin-loaded liposomes affected the osteogenic differentiation. The implication of this study is that the type of liposome should be selected based on the purpose of the application.

Modifications of Polymeric Membranes Used in Guided Tissue and Bone Regeneration

Guided tissue/bone regeneration (GTR/GBR) is a widely used procedure in contemporary dentistry. To achieve the required results of tissue regeneration, soft tissues that reproduce quickly are separated from the slow-growing bone tissue by membranes. Many types of membranes are currently in use, but none of them fulfil all of the desired features. To address this issue, further research on developing new membranes with better separation characteristics, such as membrane modification, is needed. Many of the current innovative modified materials are still in the phase of in vitro and experimental studies. A collective review on new trends in membrane modification to GTR/GBR is needed due to the widespread use of polymeric membranes and the constant development in the field of dentistry. Therefore, the aim of this review was to present an overview of polymeric membrane modifications to the GTR/GBR reported in the literature. The authors searched databases, including PubMed, SCOPUS, Web of Science, and OVID, for relevant studies that were published during 1999-2019. The following keywords were used: guided tissue regeneration, membranes, coating, and modification. A total of 17 papers were included in this review. Furthermore, the articles were divided into three groups that were based on the type of membrane modification: antibiotic coating, ion-use modifications, and others modifications, thus providing an overview of current existing knowledge in the field and encouraging further research. The results of included studies on modified barrier membranes seem to be promising, both in terms of safety and benefits for patients. However, modifications result in a large spectrum of effects. Further clinical studies are needed on a large group of patients to clearly confirm the effects that were observed in animal and in vitro studies.

Promising Biomolecules

The osteochondral defect (OD) comprises the articular cartilage and its subchondral bone. The treatment of these lesions remains as one of the most problematic clinical issues, since these defects include different tissues, requiring distinct healing approaches. Among the growing applications of regenerative medicine, clinical articular cartilage repair has been used for two decades, and it is an effective example of translational medicine; one of the most used cell-based repair strategies includes implantation of autologous cells in degradable scaffolds such as alginate, agarose, collagen, chitosan, chondroitin sulfate, cellulose, silk fibroin, hyaluronic acid, and gelatin, among others. Concerning the repair of osteochondral defects, tissue engineering and regenerative medicine started to design single- or bi-phased scaffold constructs, often containing hydroxyapatite-collagen composites, usually used as a bone substitute. Biomolecules such as natural and synthetic have been explored to recreate the cartilage-bone interface through multilayered biomimetic scaffolds. In this chapter, a succinct description about the most relevant natural and synthetic biomolecules used on cartilage and bone repair, describing the procedures to obtain these biomolecules, their chemical structure, common modifications to improve its characteristics, and also their application in the biomedical fields, is given.

Effects of Bambusa tulda on the proliferation of human stem cells

To date, the effects of Bambusa tulda on stem cells have not been thoroughly assessed. The present study aimed to evaluate the effects of Bambusa tulda extract on the morphology and proliferative potential of human mesenchymal stem cells derived from the gingiva. The stem cells were cultured in a growth medium in the presence of Bambusa tulda methanolic extract (BBT) at concentrations ranging from 0.001 to 1%. Evaluation of cell morphology and cellular proliferation as well as immunofluorescent assays for collagen I were performed on days 1, 3, 5 and 7. Stem cells in the control group displayed a fibroblast-like morphology, and BBT treatment did not produce any noticeable morphological changes. However, application of 1% BBT produced a significant increase in cell proliferation. BBT, particularly at the concentration of 1%, also caused a noticeable increase of collagen I expression at day 1 and day 3. Based on these findings, it was concluded that BBT exerted beneficial effects on the proliferation of mesenchymal stem cells and enhanced collagen I expression at early time points.

Evaluation of the effects of dimethylsulphoxide on morphology, cellular viability, mRNA, and protein expression of stem cells culture in growth media

The aim of this study was to evaluate the effects of differential concentration of dimethylsulphoxide (DMSO) on the morphology, cell viability, mRNA, and protein expression of stem cells obtained from the intraoral area. Stem cells derived obtained from gingiva were cultured in a growth medium in the presence of DMSO at concentrations ranging from 0.01 to 10%. The morphology and cellular viability were evaluated on days 1, 3, 5, 7 and 10. Quantitative polymerase chain reaction was used to evaluate the mRNA levels of collagen I and Runt-related transcription factor 2 (Runx2). Immunofluorescent assays were performed for Runx2 and collagen I, and protein expressions were measured, including those of Runx2 and collagen I using western blot analysis. Cells in the control group showed normal fibroblast morphology in the growth media. Cells from the higher DMSO concentration were significantly different compared to the control. The decrease in cell viability was noted in the higher concentration. A notable change in collagen I expression was noted at the higher concentrations of DMSO groups. Based on these findings, it was concluded that DMSO may have detrimental effects on the cell morphology and viability of mesenchymal stem cells. The results also suggest that DMSO has toxic effects via reduced collagen I expression.

Short-term application of dexamethasone on stem cells derived from human gingiva reduces the expression of RUNX2 and β-catenin

Objective

Next-generation sequencing was performed to evaluate the effects of short-term application of dexamethasone on human gingiva-derived mesenchymal stem cells.

Methods

Human gingiva-derived stem cells were treated with a final concentration of 10⁻⁷M dexamethasone and the same concentration of vehicle control. This was followed by mRNA sequencing and data analysis, gene ontology and pathway analysis, quantitative real-time polymerase chain reaction of mRNA, and western blot analysis of RUNX2 and β-catenin.

Results

In total, 26,364 mRNAs were differentially expressed. Comparison of the results of dexamethasone versus control at 2 hours revealed that 7 mRNAs were upregulated and 25 mRNAs were downregulated. The application of dexamethasone reduced the expression of RUNX2 and β-catenin in human gingiva-derived mesenchymal stem cells.

Conclusion

The effects of dexamethasone on stem cells were evaluated with mRNA sequencing, and validation of the expression was performed with qualitative real-time polymerase chain reaction and western blot analysis. The results of this study can provide new insights into the role of mRNA sequencing in maxillofacial areas.

Evaluation of the maintenance of stemness, viability, and differentiation potential of gingiva-derived stem-cell spheroids

Gingiva-derived stem cells have been applied for tissue-engineering purposes and may be considered a favorable source of mesenchymal stem cells as harvesting stem cells from the mandible or maxilla may be performed with ease under local anesthesia. The present study was performed to fabricate stem-cell spheroids using concave microwells and to evaluate the maintenance of stemness, viability, and differentiation potential. Gingiva-derived stem cells were isolated, and the stem cells of 4×10⁵ (group A) or 8×10⁵ (group B) cells were seeded into polydimethylsiloxane-based, concave micromolds with 600 µm diameters. The morphology of the microspheres and the change of the diameters of the spheroids were evaluated. The viability of spheroids was qualitatively analyzed via Live/Dead kit assay. A cell viability analysis was performed on days 1, 3, 6, and 12 with Cell Counting Kit-8. The maintenance of stemness was evaluated with immunocytochemical staining using SSEA-4, TRA-1-60(R) (positive markers), and SSEA-1 (negative marker). Osteogenic, adipogenic, and chondrogenic differentiation potential was evaluated by incubating spheroids in osteogenic, adipogenic and chondrogenic induction medium, respectively. The gingiva-derived stem cells formed spheroids in the concave microwells. The diameters of the spheroids were larger in group A than in group B. The majority of cells in the spheroids emitted green fluorescence, indicating the presence of live cells at day 6. At day 12, the majority of cells in the spheroids emitted green fluorescence, and a small portion of red fluorescence was also noted, which indicated the presence of dead cells. The spheroids were positive for the stem-cell markers SSEA-4 and TRA-1-60(R) and were negative for SSEA-1, suggesting that these spheroids primarily contained undifferentiated human stem cells. Osteogenic, adipogenic, and chondrogenic differentiation was more evident with an increase of incubation time: Mineralized extracellular deposits were observed following Alizarin Red S staining at days 14 and 21; oil globules were increased at day 18 when compared with day 6; and Alcian blue staining was more evident at day 18 when compared with day 6. Within the limits of this study, stem-cell spheroids from gingival cells maintained the stemness, viability, and differentiation potential during the experimental periods. This method may be applied for a promising strategy for stem-cell therapy.

Composite biopolymers for bone regeneration enhancement in bony defects

For the past century, various biomaterials have been used in the treatment of bone defects and fractures. Their role as potential substitutes for human bone grafts increases as donors become scarce. Metals, ceramics and polymers are all materials that confer different advantages to bone scaffold development. For instance, biocompatibility is a highly desirable property for which naturally-derived polymers are renowned. While generally applied separately, the use of biomaterials, in particular natural polymers, is likely to change, as biomaterial research moves towards mixing different types of materials in order to maximize their individual strengths. This review focuses on osteoconductive biocomposite scaffolds which are constructed around natural polymers and their performance at the in vitro/in vivo stages and in clinical trials.

Effects of Cimicifugae Rhizoma on the osteogenic and adipogenic differentiation of stem cells

Cimicifugae Rhizoma, a herb with a long history of use in traditional Oriental medicine is reported to have anti-inflammatory, antioxidant, anti-complement and anticancer effects. The aim of the present study was to evaluate the effects of Cimicifugae Rhizoma extracts on the osteogenic and adipogenic differentiation of human stem cells derived from gingiva. Stem cells derived from gingiva were grown in the presence of Cimicifugae Rhizoma at final concentrations of 0.1, 1 and 10 µg/ml. Cell proliferation analyses were performed at day 15. For osteogenic differentiation experiments, the stem cells were cultured in osteogenic media containing β-glycerophosphate, ascorbic acid-2-phosphate and dexamethasone, and osteogenic differentiation was evaluated by analysis of osteocalcin expression at 21 days. For adipogenic differentiation experiments, the stem cells were grown in adipogenic induction medium, and the adipogenic differentiation was evaluated by analysis of adipocyte fatty acid-binding protein at day 14. The cultures grown in the presence of 0.1 µg/ml Cimicifugae Rhizoma showed a significant increase in cellular proliferation at day 15 compared with the control group. The relative osteogenic differentiation in the presence of Cimicifugae Rhizoma for the 0.1, 1 and 10 µg/ml groups was 171.5±13.7, 125.6±28.7 and 150.5±9.0, respectively, when that of the untreated control group on day 21 was considered to be 100%. The relative adipogenic differentiation at day 14 of the 0.1, 1 and 10 µg/ml groups in the presence of Cimicifugae Rhizoma was 97.5±15.0, 102.9±12.8 and 87.0±6.8%, respectively when that of the untreated control group on day 14 was considered to be 100%. Within the limits of this study, Cimicifugae Rhizoma increased the proliferation of stem cells derived from the gingiva, and low concentrations of Cimicifugae Rhizoma may increase the osteogenic differentiation of stem cells.

Gingival Mesenchymal Stem/Progenitor Cells: A Unique Tissue Engineering Gem

The human gingiva, characterized by its outstanding scarless wound healing properties, is a unique tissue and a pivotal component of the periodontal apparatus, investing and surrounding the teeth in their sockets in the alveolar bone. In the last years gingival mesenchymal stem/progenitor cells (G-MSCs), with promising regenerative and immunomodulatory properties, have been isolated and characterized from the gingival lamina propria. These cells, in contrast to other mesenchymal stem/progenitor cell sources, are abundant, readily accessible, and easily obtainable via minimally invasive cell isolation techniques. The present review summarizes the current scientific evidence on G-MSCs' isolation, their characterization, the investigated subpopulations, the generated induced pluripotent stem cells- (iPSC-) like G-MSCs, their regenerative properties, and current approaches for G-MSCs' delivery. The review further demonstrates their immunomodulatory properties, the transplantation preconditioning attempts via multiple biomolecules to enhance their attributes, and the experimental therapeutic applications conducted to treat multiple diseases in experimental animal models in vivo. G-MSCs show remarkable tissue reparative/regenerative potential, noteworthy immunomodulatory properties, and primary experimental therapeutic applications of G-MSCs are very promising, pointing at future biologically based therapeutic techniques, being potentially superior to conventional clinical treatment modalities.

Tetracycline hydrochloride loaded regenerated cellulose composite membranes with controlled release and efficient antibacterial performance

Fabrication of cellulose based composites with controlled release and efficient antibacterial performances is of general interest in biomedical areas.

Formation of size-controllable spheroids using gingiva-derived stem cells and concave microwells: Morphology and viability tests

Human mesenchymal stem cells have previously been isolated and characterized from the gingiva, and gingiva-derived stem cells have been applied for tissue engineering purposes. The present study was performed to generate size-controllable stem cell spheroids using concave microwells. Gingiva-derived stem cells were isolated, and the stem cells of 1×10⁵ (group A) or 2×10⁵ (group B) cells were seeded in polydimethylsiloxane-based, concave micromolds with 600 µm diameters. The morphology of the microspheres was viewed under an inverted microscope, and the changes in the diameter and cell viability were analyzed. The gingiva-derived stem cells formed spheroids in the concave microwells. The diameters of the spheroids were larger in group A compared to group B. No significant changes in shape or diameter were noted with increases in incubation time. Cell viability was higher in group B at each time point when compared with group A. Within the limits of the study, the size-controllable stem cell spheroids could be generated from gingival cells using microwells. The shape of the spheroids and their viability were clearly maintained during the experimental periods.