Effects of hydroxyapatite nanostructure on channel surface of porcine acellular dermal matrix scaffold on cell viability and osteogenic differentiation of human periodontal ligament stem cells

Stem Cells in the Periodontium-Anatomically Related Yet Physiologically Diverse

Periodontitis is a complex chronic disease discernible by the deterioration of periodontal tissue. The goal of periodontal therapy is to achieve complete tissue regeneration, and one of the most promising treatment options is to harness the regenerative potential of stem cells available within the periodontal complex. Periodontal ligament stem cells, gingival mesenchymal stem cells, oral periosteal stem cells, and dental follicle stem cells have structural similarities, but their immunological responses and features differ. The qualities of diverse periodontal stem cells, their immune-modulatory effects, and variances in their phenotypes and characteristics will be discussed in this review. Although there is evidence on each stem cell population in the periodontium, understanding the differences in markers expressed, the various research conducted so far on their regenerative potential, will help in understanding which stem cell population will be a better candidate for tissue engineering. The possibility of selecting the most amenable stem cell population for optimal periodontal regeneration and the development and current application of superior tissue engineering treatment options such as autologous transplantation, three-dimensional bioengineered scaffolds, dental stem cell-derived extracellular vesicles will be explored.

Effect of Nicotine and Porphyromonas gingivalis on the Differentiation Properties of Periodontal Ligament Fibroblasts

Objectives This study aimed to evaluate the effect of Porphyromonas gingivalis and nicotine on the in vitro osteogenic differentiation of periodontal ligament (PDL) fibroblasts.

Materials and Methods PDLs were cultured in Dulbecco’s modified Eagle’s medium containing 10% fetal bovine serum at 37°C under 5% CO ₂ and 100% humidified atmosphere. Cells were incubated with various concentrations of nicotine and P. gingivalis extracts, and cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. To study cell differentiation, PDLs (5 × 10 ⁴ cells) were treated with the osteogenic differentiation medium containing 10 mM β-glycerophosphate, 10 nM dexamethasone, 50 mg/mL ascorbic acid, 1 μM nicotine, and 50 µg/mL P. gingivalis lysate. mRNA samples were collected at 0, 7, and 14 days. Odontogenic-related gene expression, namely, Runt-related transcription factor 2 ( Runx2 ), collagen type I ( COL1A1 ), and alkaline phosphatase ( ALP ) was determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Calcified nodule formation was determined on day 28 using Alizarin Red S. Analysis of variance and Tukey’s test were used to compare the difference among groups at significant level of p < 0.05.

Results It showed that 50 µg/mL of P. gingivalis lysate and 1 µM of nicotine showed no toxicity to PDLs. Runx2 , COL1A1 , and ALP expression were found to decrease significantly after 7 days of treatment, while osteocalcin expression was found to decrease after 14 days. The nodule formation in the control group was much greater in both number and size of nodules than in experimental groups, which implied a positive sign of calcium deposition in controls.

Conclusion The results indicated that nicotine and P. gingivalis showed adverse effect on osteogenic differentiation properties of PDLs.

The useful agent to have an ideal biological scaffold

Tissue engineering which is applied in regenerative medicine has three basic components: cells, scaffolds and growth factors. This multidisciplinary field can regulate cell behaviors in different conditions using scaffolds and growth factors. Scaffolds perform this regulation with their structural, mechanical, functional and bioinductive properties and growth factors by attaching to and activating their receptors in cells. There are various types of biological extracellular matrix (ECM) and polymeric scaffolds in tissue engineering. Recently, many researchers have turned to using biological ECM rather than polymeric scaffolds because of its safety and growth factors. Therefore, selection the right scaffold with the best properties tailored to clinical use is an ideal way to regulate cell behaviors in order to repair or improve damaged tissue functions in regenerative medicine. In this review we first divided properties of biological scaffold into intrinsic and extrinsic elements and then explain the components of each element. Finally, the types of scaffold storage methods and their advantages and disadvantages are examined.

Substrate Topography Regulates Differentiation of Annulus Fibrosus-Derived Stem Cells via CAV1-YAP-Mediated Mechanotransduction

Regeneration of annulus fibrosus (AF) through tissue engineering techniques shows promise as a treatment for patients with degenerative disc disease (DDD). Yet, it remains challenging because of the intrinsic heterogeneity of AF tissue and shortage of in-depth knowledge of its structure-function correlation. In the current study, we fabricated fibrous poly(ether carbonate urethane)urea (PECUU) scaffolds with various fiber sizes to mimic the microstructural feature of native AF and aimed to regulate the differentiation of AF-derived stem cells (AFSCs) by controlling the topographical cues of the scaffold. We found that the morphology of AFSCs varied significantly on scaffolds with various fiber sizes. Meanwhile, the expression of the phenotypic marker genes of outer AF was up-regulated on scaffolds with large fibers. Meanwhile, enhanced expression of the phenotypic marker genes of inner AF was seen on scaffolds with small fibers. Such topography-dependent gene expression in AFSCs approximated the biochemical profile of AF tissue in various zones. Moreover, cell spreading and nucleus translocation of Yes-associated protein (YAP) were facilitated with increased fiber size. Formation and maturation of focal adhesions of AFSCs were also promoted. We also found that Caveolin-1 (CAV1) positively modulated the mechano-responses of YAP in response to substrate topography. In conclusion, depending on the activation of the CAV1-YAP mechanotransduction axis, tuning the fiber size of scaffolds can effectively induce changes in cell shape, adhesions, and extracellular matrix expression. This work may therefore provide new insights in the design of novel materials toward AF tissue regeneration.

Regulation of differentiation of annulus fibrosus-derived stem cells using heterogeneous electrospun fibrous scaffolds

Background

Tissue engineering of the annulus fibrosus (AF) shows promise as a treatment for patients with degenerative disc disease (DDD). However, it remains challenging due to the intrinsic heterogeneity of AF tissue. Fabrication of scaffolds recapitulating the specific cellular, componential, and microstructural features of AF, therefore, is critical to successful AF tissue regeneration.

Methods

Poly-L-lactic acid (PLLA) fibrous scaffolds with various fiber diameters and orientation were prepared to mimic the microstructural characteristics of AF tissue using electrospinning technique. AF-derived stem cells (AFSCs) were cultured on the PLLA fibrous scaffolds for 7 days.

Results

The morphology of AFSCs significantly varied when cultured on the scaffolds with various fiber diameters and orientation. AFSCs were nearly round on scaffolds with small fibers. However, they became spindle-shaped on scaffolds with large fibers. Meanwhile, upregulated expression of collagen-I gene happened in cells cultured on scaffolds with large fibers, while enhanced expression of collagen-II and aggrecan genes was seen on scaffolds with small fibers. The production of related proteins also showed similar trends. Further, culturing AFSCs on a heterogeneous scaffold by overlaying membranes with different fiber sizes led to the formation of a hierarchical structure approximating native AF tissue.

Conclusion

Findings from this study demonstrate that fibrous scaffolds with different fiber sizes effectively promoted the differentiation of AFSCs into specific cells similar to the types of cells at various AF zones. It also provides a valuable reference for regulation of cell differentiation and fabrication of engineered tissues with complex hierarchical structures using the physical cues of scaffolds.

The translational potential of this article

Effective AF repair is an essential need for treating degenerative disc disease. Tissue engineering is a promising approach to achieving tissue regeneration and restoring normal functions of tissues. By mimicking the key structural features of native AF tissue, including fiber size and alignment, this study deciphered the effect of scaffold materials on the cell differentiation and extracellular matrix deposition, which provides a solid basis for designing new strategies toward more effective AF repair and regeneration.

Effects of Electrical Stimulation on Stem Cells

Recent interest in developing new regenerative medicine- and tissue engineering-based treatments has motivated researchers to develop strategies for manipulating stem cells to optimize outcomes in these potentially, game-changing treatments. Cells communicate with each other, and with their surrounding tissues and organs via electrochemical signals. These signals originate from ions passing back and forth through cell membranes and play a key role in regulating cell function during embryonic development, healing, and regeneration. To study the effects of electrical signals on cell function, investigators have exposed cells to exogenous electrical stimulation and have been able to increase, decrease and entirely block cell proliferation, differentiation, migration, alignment, and adherence to scaffold materials. In this review, we discuss research focused on the use of electrical stimulation to manipulate stem cell function with a focus on its incorporation in tissue engineering-based treatments.

Application of laser scanning confocal microscopy in the soft tissue exquisite structure for 3D scan

Three-dimensional (3D) printing is a new developing technology for printing individualized materials swiftly and precisely in the field of biological medicine (especially tissue-engineered materials). Prior to printing, it is necessary to scan the structure of the natural biological tissue, then construct the 3D printing digital model through optimizing the scanned data. By searching the literatures, magazines at home and abroad, this article reviewed the current status, main processes and matters needing attention of confocal laser scanning microscope (LSCM) in the application of soft tissue fine structure 3D scanning, empathizing the significance of LSCM in this field.

Soft Tissue Augmentation Techniques and Materials Used in the Oral Cavity: An Overview

PURPOSE

Oral soft tissue augmentation or grafting procedures are often necessary to achieve proper wound closure after deficits resulting from tumor excision, clefts, trauma, dental implants, and tooth recessions.

MATERIALS AND METHODS

Autologous soft tissue grafts still remain the gold standard to acquire a functionally adequate zone of keratinized attached gingiva. However, soft tissue substitutes are more commonly used because they minimize morbidity and shorten surgical time.

RESULTS

This review aimed to assess soft tissue grafting techniques and materials used in the oral cavity from existing literature. There are a large variety of materials and techniques, including grafts, local flaps, allogenic derived matrices such as acellular dermal allograft, xenogenic tissue matrices from animal origin, and synthetic materials.

CONCLUSIONS

Tissue engineering of oral mucosa represents an interesting alternative to obtain sufficient autologous tissue for reconstructing oral wounds using biodegradable scaffolds, and may improve vascularization and epithelialization, which are critical for successful outcomes.

PTH/SDF-1α cotherapy promotes proliferation, migration and osteogenic differentiation of human periodontal ligament stem cells

OBJECTIVES

Stromal cell-derived factor-1α (SDF-1α) plays an important role in tissue regeneration in various tissues including the periodontium. A potential limitation for its use derives from its sensitivity to cleavage by dipeptidyl peptidase-IV (DPP-IV). Parathyroid hormone (PTH) reduces enzymatic activity of DPP-IV and is suggested to be a promising agent for periodontal tissue repair. The purpose of this study was to provide insight into how SDF-1α and intermittent PTH treatment might affect proliferation, migration and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) in vitro.

MATERIALS AND METHODS

PDLSCs were isolated by the limiting dilution method. Surface markers were quantified by flow cytometry. Cell-counting kit-8 (CCK8), cell migration assay, alkaline phosphatase (ALP) activity assay, alizarin red staining and RT-PCR were used to determine viability, migration and osteogenic differentiation of PDLSCs.

RESULTS

PDLSCs were positive for CD44, CD73, CD90, CD105, CD166 and STRO-1 and negative for CD14, CD34 and CD45. PTH/SDF-1α cotherapy significantly promoted cell proliferation, chemotactic capability, ALP activity and mineral deposition (P<.05). Gene expression level of bone sialoprotein (BSP), runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) were all up-regulated (P<.05).

CONCLUSIONS

PTH/SDF-1α cotherapy promoted proliferation, migration and osteogenic differentiation of PDLSCs in vitro. Cotherapy seemed to have potential to promote periodontal tissue regeneration by facilitating chemotaxis of PDLSCs to the injured site, followed by promoting proliferation and osteogenic differentiation of these cells.

When 1+1>2: Nanostructured composites for hard tissue engineering applications

Multicomponent, synergistic and multifunctional nanostructures have taken over the spotlight in the realm of biomedical nanotechnologies. The most prospective materials for bone regeneration today are almost exclusively composites comprising two or more components that compensate for the shortcomings of each one of them alone. This is quite natural in view of the fact that all hard tissues in the human body, except perhaps the tooth enamel, are composite nanostructures. This review article highlights some of the most prospective breakthroughs made in this research direction, with the hard tissues in main focus being those comprising bone, tooth cementum, dentin and enamel. The major obstacles to creating collagen/apatite composites modeled after the structure of bone are mentioned, including the immunogenicity of xenogeneic collagen and continuously failing attempts to replicate the biomineralization process in vitro. Composites comprising a polymeric component and calcium phosphate are discussed in light of their ability to emulate the soft/hard composite structure of bone. Hard tissue engineering composites created using hard material components other than calcium phosphates, including silica, metals and several types of nanotubes, are also discoursed on, alongside additional components deliverable using these materials, such as cells, growth factors, peptides, antibiotics, antiresorptive and anabolic agents, pharmacokinetic conjugates and various cell-specific targeting moieties. It is concluded that a variety of hard tissue structures in the body necessitates a similar variety of biomaterials for their regeneration. The ongoing development of nanocomposites for bone restoration will result in smart, theranostic materials, capable of acting therapeutically in direct feedback with the outcome of in situ disease monitoring at the cellular and subcellular scales. Progress in this research direction is expected to take us to the next generation of biomaterials, designed with the purpose of fulfilling Daedalus' dream - not restoring the tissues, but rather augmenting them.

Osteogenic Potential of Dental Mesenchymal Stem Cells in Preclinical Studies: A Systematic Review Using Modified ARRIVE and CONSORT Guidelines

Background and Objective. Dental stem cell-based tissue engineered constructs are emerging as a promising alternative to autologous bone transfer for treating bone defects. The purpose of this review is to systematically assess the preclinical in vivo and in vitro studies which have evaluated the efficacy of dental stem cells on bone regeneration. Methods. A literature search was conducted in Ovid Medline, Embase, PubMed, and Web of Science up to October 2014. Implantation of dental stem cells in animal models for evaluating bone regeneration and/or in vitro studies demonstrating osteogenic potential of dental stem cells were included. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used to ensure the quality of the search. Modified ARRIVE (Animal research: reporting in invivo experiments) and CONSORT (Consolidated reporting of trials) were used to critically analyze the selected studies. Results. From 1914 citations, 207 full-text articles were screened and 137 studies were included in this review. Because of the heterogeneity observed in the studies selected, meta-analysis was not possible. Conclusion. Both in vivo and in vitro studies indicate the potential use of dental stem cells in bone regeneration. However well-designed randomized animal trials are needed before moving into clinical trials.

Cranial vault reconstruction with bone morphogenetic protein, calcium phosphate, acellular dermal matrix, and calcium alginate in mice

PURPOSE

To evaluate experimental cranial vault reconstructions, by combining bone morphogenetic protein type 2 (BMP-2) and different matrices.

METHODS

Fourty-nine animals were initially included (seven per group). We designed an experimental, open, prospective and comparative study, divided in seven groups: 1 - BMP-2+calcium phosphate (BT); 2 - BMP-2+acellular dermal matrix (BM); 3 - BMP-2+calcium alginate (BA); 4 - TCP; 5 - MDM; 6 - ALG; 7 - Bone autograft (BAG). A bone failure was created in left parietal bone of adult male mice. At the same procedure reconstruction was performed. After five weeks, animals were sacrificed, and reconstruction area was removed to histological analysis. After exclusion due to death or infection, thirty-eight animals were evaluated (BT=5; BM=6; BA=6; TCP=7; MDM=3; ALG=6; BAG=5).

RESULTS

A higher incidence of infection has occurred in MDM group (57%, P=0.037). In cortical fusion, groups BAG, TCP, and BMP-2+TCP (BT) obtained the best scores, comparing to the others (P=0.00846). In new bone formation, groups BT, BAG, and TCP have presented the best scores (P=0.00835). When neovascularization was considered, best groups were BMP-2+MDM (BM), BMP-2+ALG (BA), TCP, and MDM (P=0.001695). BAG group was the best in bone marrow formation, followed by groups BT and TCP (P=0.008317).

CONCLUSIONS

Bone morphogenetic protein type 2 increased bone regeneration in experimental skull reconstruction, especially when combined to calcium phosphate. Such association was even comparable to bone autograft, the gold-standard treatment, in some histological criteria.