Transplanted Human Bone Marrow Mesenchymal Stem Cells Seeded onto Peptide Hydrogel Decrease Alveolar Bone Loss

An Exploration of the Role of Osteoclast Lineage Cells in Bone Tissue Engineering

Bone defects because of age, trauma, and surgery, which are exacerbated by medication side effects and common diseases such as osteoporosis, diabetes, and rheumatoid arthritis, are a problem of epidemic scale. The present clinical standard for treating these defects includes autografts and allografts. Although both treatments can promote robust regenerative outcomes, they fail to strike a desirable balance of availability, side effect profile, consistent regenerative efficacy, and affordability. This difficulty has contributed to the rise of bone tissue engineering (BTE) as a potential avenue through which enhanced bone regeneration could be delivered. BTE is founded upon a paradigm of using biomaterials, bioactive factors, osteoblast lineage cells (ObLCs), and vascularization to cue deficient bone tissue into a state of regeneration. Despite promising preclinical results, BTE has had modest success in being translated into the clinical setting. One barrier has been the simplicity of its paradigm relative to the complexity of biological bone. Therefore, this paradigm must be critically examined and expanded to better account for this complexity. One potential avenue for this is a more detailed consideration of osteoclast lineage cells (OcLCs). Although these cells ostensibly oppose ObLCs and bone regeneration through their resorptive functions, a myriad of investigations have shed light on their potential to influence bone equilibrium in more complex ways through their interactions with both ObLCs and bone matrix. Most BTE research has not systematically evaluated their influence. Yet contrary to expectations associated with the paradigm, a selection of BTE investigations has demonstrated that this influence can enhance bone regeneration in certain contexts. In addition, much work has elucidated the role of many controllable scaffold parameters in both inhibiting and stimulating the activity of OcLCs in parallel to bone regeneration. Therefore, this review aims to detail and explore the implications of OcLCs in BTE and how they can be leveraged to improve upon the existing BTE paradigm.

Supramolecular Peptide Nanofiber Hydrogels for Bone Tissue Engineering: From Multihierarchical Fabrications to Comprehensive Applications

Bone tissue engineering is becoming an ideal strategy to replace autologous bone grafts for surgical bone repair, but the multihierarchical complexity of natural bone is still difficult to emulate due to the lack of suitable biomaterials. Supramolecular peptide nanofiber hydrogels (SPNHs) are emerging biomaterials because of their inherent biocompatibility, satisfied biodegradability, high purity, facile functionalization, and tunable mechanical properties. This review initially focuses on the multihierarchical fabrications by SPNHs to emulate natural bony extracellular matrix. Structurally, supramolecular peptides based on distinctive building blocks can assemble into nanofiber hydrogels, which can be used as nanomorphology-mimetic scaffolds for tissue engineering. Biochemically, bioactive motifs and bioactive factors can be covalently tethered or physically absorbed to SPNHs to endow various functions depending on physiological and pharmacological requirements. Mechanically, four strategies are summarized to optimize the biophysical microenvironment of SPNHs for bone regeneration. Furthermore, comprehensive applications about SPNHs for bone tissue engineering are reviewed. The biomaterials can be directly used in the form of injectable hydrogels or composite nanoscaffolds, or they can be used to construct engineered bone grafts by bioprinting or bioreactors. Finally, continuing challenges and outlook are discussed.

Chirality-induced bionic scaffolds in bone defects repair-a review

Due to lack of amino sugar with aging, people will suffer from various epidemic bone diseases called "undead cancer" by the World Health Organization. The key problem in bone tissue engineering that has not been completely resolved is the repair of critical large-scale bone and cartilage defects. The chirality of the extracellular matrix plays a decisive role in the physiological activity of bone cells and the occurrence of bone tissue, but the mechanism of chirality in regulating cell adhesion and growth is still in the early stage of exploration. This paper reviews the application progress of chirality-induced bionic scaffolds in bone defects repair based on "soft" and "hard" scaffolds. The aim is to summarize the effects of different chiral structures (L-shaped and D-shaped) in the process of inducing bionic scaffolds in bone defects repair. In addition, many technologies and methods as well as issues worthy of special consideration for preparing chirality-induced bionic scaffolds are also introduced. We expect that this work can provide inspiring ideas for designing new chirality-induced bionic scaffolds and promote the development of chirality in bone tissue engineering. This article is protected by copyright. All rights reserved.

Self-assembling peptides as vectors for local drug delivery and tissue engineering applications

Molecular self-assembly has forged a new era in the development of advanced biomaterials for local drug delivery and tissue engineering applications. Given their innate biocompatibility and biodegradability, self-assembling peptides (SAPs) have come in the spotlight of such applications. Short and water-soluble SAP biomaterials associated with enhanced pharmacokinetic (PK) and pharmacodynamic (PD) responses after the topical administration of the therapeutic systems, or improved regenerative potential in tissue engineering applications will be the focus of the current review. SAPs are capable of generating supramolecular structures using a boundless array of building blocks, while peptide engineering is an approach commonly pursued to encompass the desired traits to the end composite biomaterials. These two elements combined, expand the spectrum of SAPs multi-functionality, constituting them potent biomaterials for use in various biomedical applications.

Stem cell therapies for periodontal tissue regeneration: a network meta-analysis of preclinical studies

Background

Periodontal tissue regeneration (PTR) is the ultimate goal of periodontal therapy. Currently, stem cell therapy is considered a promising strategy for achieving PTR. However, there is still no conclusive comparison that distinguishes clear hierarchies among different kinds of stem cells.

Methods

A systematic review and network meta-analysis (NMA) was performed using MEDLINE (via PubMed), EMBASE, and Web of Science up to February 2020. Preclinical studies assessing five types of stem cells for PTR were included; the five types of stem cells included periodontal ligament-derived stem cells (PDLSCs), bone marrow-derived stem cells (BMSCs), adipose tissue-derived stem cells (ADSCs), dental pulp-derived stem cells (DPSCs), and gingival-derived stem cells (GMSCs). The primary outcomes were three histological indicators with continuous variables: newly formed alveolar bone (NB), newly formed cementum (NC), and newly formed periodontal ligament (NPDL). We performed pairwise meta-analyses using a random-effects model and then performed a random-effects NMA using a multivariate meta-analysis model.

Results

Sixty preclinical studies assessing five different stem cell-based therapies were identified. The NMA showed that in terms of NB, PDLSCs (standardized mean difference 1.87, 95% credible interval 1.24 to 2.51), BMSCs (1.88, 1.17 to 2.59), and DPSCs (1.69, 0.64 to 2.75) were statistically more efficacious than cell carriers (CCs). In addition, PDLSCs were superior to GMSCs (1.49, 0.04 to 2.94). For NC, PDLSCs (2.18, 1.48 to 2.87), BMSCs (2.11, 1.28 to 2.94), and ADSCs (1.55, 0.18 to 2.91) were superior to CCs. For NPDL, PDLSCs (1.69, 0.92 to 2.47) and BMSCs (1.41, 0.56 to 2.26) were more efficacious than CCs, and PDLSCs (1.26, 0.11 to 2.42) were superior to GMSCs. The results of treatment hierarchies also demonstrated that the two highest-ranked interventions were PDLSCs and BMSCs.

Conclusion

PDLSCs and BMSCs were the most effective and well-documented stem cells for PTR among the five kinds of stem cells evaluated in this study, and there was no statistical significance between them. To translate the stem cell therapies for PTR successfully in the clinic, future studies should utilize robust experimental designs and reports.

EphrinB2 regulates osteogenic differentiation of periodontal ligament stem cells and alveolar bone defect regeneration in beagles

EphrinB2, a membrane protein regulating bone homeostasis, has been demonstrated to induce osteogenic gene expression in periodontal ligament fibroblasts. The aim of this study was to explore the effects of ephrinB2 on osteogenic differentiation of periodontal ligament stem cells and on alveolar bone regeneration in vivo. We assessed the osteogenic gene expression and osteogenic differentiation potential of ephrinB2-modified human and canine periodontal ligament stem cells, in which ephrinB2 expression was upregulated via lentiviral vector transduction. EphrinB2-modified canine periodontal ligament stem cells combined with PuraMatrix were delivered to critical-sized alveolar bone defects in beagles to evaluate bone regeneration. Results showed that ephrinB2 overexpression enhanced osteogenic gene transcription and mineral deposition in both human and canine periodontal ligament stem cells. Animal experiments confirmed that ephrinB2-modified canine periodontal ligament stem cells + PuraMatrix resulted in greater trabecular bone volume per tissue volume and trabecular thickness compared with other groups. Our study demonstrated that ephrinB2 promoted osteogenic differentiation of periodontal ligament stem cells and alveolar bone repair in beagles, highlighting its therapeutic potential for the treatment of alveolar bone damage.

Efficacy of stem cells on periodontal regeneration: Systematic review of pre-clinical studies

This systematic review aims to evaluate mesenchymal stem cells (MSC) periodontal regenerative potential in animal models. MEDLINE, EMBASE and LILACS databases were searched for quantitative pre-clinical controlled animal model studies that evaluated the effect of local administration of MSC on periodontal regeneration. The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines. Twenty-two studies met the inclusion criteria. Periodontal defects were surgically created in all studies. In seven studies, periodontal inflammation was experimentally induced following surgical defect creation. Differences in defect morphology were identified among the studies. Autogenous, alogenous and xenogenous MSC were used to promote periodontal regeneration. These included bone marrow-derived MSC, periodontal ligament (PDL)-derived MSC, dental pulp-derived MSC, gingival margin-derived MSC, foreskin-derived induced pluripotent stem cells, adipose tissue-derived MSC, cementum-derived MSC, periapical follicular MSC and alveolar periosteal cells. Meta-analysis was not possible due to heterogeneities in study designs. In most of the studies, local MSC implantation was not associated with adverse effects. The use of bone marrow-derived MSC for periodontal regeneration yielded conflicting results. In contrast, PDL-MSC consistently promoted increased PDL and cementum regeneration. Finally, the adjunct use of MSC improved the regenerative outcomes of periodontal defects treated with membranes or bone substitutes. Despite the quality level of the existing evidence, the current data indicate that the use of MSC may provide beneficial effects on periodontal regeneration. The various degrees of success of MSC in periodontal regeneration are likely to be related to the use of heterogeneous cells. Thus, future studies need to identify phenotypic profiles of highly regenerative MSC populations.

Osteogenic differentiation of human mesenchymal stem cells promotes mineralization within a biodegradable peptide hydrogel

An attractive strategy for the regeneration of tissues has been the use of extracellular matrix analogous biomaterials. Peptide-based fibrillar hydrogels have been shown to mimic the structure of extracellular matrix offering cells a niche to undertake their physiological functions. In this study, the capability of an ionic-complementary peptide FEFEFKFK (F, E, and K are phenylalanine, glutamic acid, and lysine, respectively) hydrogel to host human mesenchymal stem cells in three dimensions and induce their osteogenic differentiation is demonstrated. Assays showed sustained cell viability and proliferation throughout the hydrogel over 12 days of culture and these human mesenchymal stem cells differentiated into osteoblasts simply upon addition of osteogenic stimulation. Differentiated osteoblasts synthesized key bone proteins, including collagen-1 (Col-1), osteocalcin, and alkaline phosphatase. Moreover, mineralization occurred within the hydrogel. The peptide hydrogel is a naturally biodegradable material as shown by oscillatory rheology and reversed-phase high-performance liquid chromatography, where both viscoelastic properties and the degradation of the hydrogel were monitored over time, respectively. These findings demonstrate that a biodegradable octapeptide hydrogel can host and induce the differentiation of stem cells and has the potential for the regeneration of hard tissues such as alveolar bone.

Cell-Based Approaches in Periodontal Regeneration: A Systematic Review and Meta-Analysis of Periodontal Defect Models in Animal Experimental Work

Various cell types have been assessed for experimental periodontal tissue regeneration in a variety of animal models. Nonetheless, the efficacy of cell-based approaches for periodontal regeneration is still controversial. Therefore, the purpose of this study was to systematically review cell-based approaches for periodontal regeneration in animal studies including a meta-analysis to obtain more clarity on their efficacy. The results of this systematic review and meta-analysis revealed that cell-based approaches have a favorable effect on periodontal tissue regeneration, as displayed by the positive effect of cell-based approaches on new bone, cementum, and periodontal ligament (PDL) formation in periodontal defects. Moreover, subgroup analysis showed a favorable effect on PDL formation by PDL-derived cells, but not by bone marrow mesenchymal stem cells (BMSCs). However, meta-analysis did not show any statistically significant differences in effect between PDL-derived cells and BMSCs. These results provide important information for the implementation of cell-based approaches in clinical practice as a routine treatment for periodontal regeneration in the future.

Stem cells regenerative properties on new rat spinal fusion model

Stem cells biology is one of the most frequent topic of physiological research of today. Spinal fusion represents common bone biology challenge. It is the indicator of osteoinduction and new bone formation on ectopic model. The purpose of this study was to establish a simple model of spinal fusion based on a rat model including verification of the possible use of titanium microplates with hydroxyapatite scaffold combined with human bone marrow-derived mesenchymal stem cells (MSCs). Spinous processes of two adjacent vertebrae were fixed in 15 Wistar rats. The space between bony vertebral arches and spinous processes was either filled with augmentation material only and covered with a resorbable collagen membrane (Group 1), or filled with augmentation material loaded with 5 × 10⁶ MSCs and covered with a resorbable collagen membrane (Group 2). The rats were sacrificed 8 weeks after the surgery. Histology, histomorphometry and micro-CT were performed. The new model of interspinous fusion was safe, easy, inexpensive, with zero mortality. We did not detect any substantial pathological changes or tumor formation after graft implantation. We observed a nonsignificant effect on the formation of new bone tissue between Group 1 and Group 2. In the group with MSCs (Group 2) we described minor inflamatory response which indicates the imunomodulational and antiinflamatory role of MSCs. In conclusion, this new model proved to be easy to use in small animals like rats.

Bone marrow mesenchymal stem cells stimulated by bFGF up-regulated protein expression in comparison with periodontal fibroblasts in vitro

OBJECTIVE

The aim of this study was to evaluate, in vitro, the role of bFGF in the proliferation and expression of collagen type I and fibronectin of dog bone marrow mesenchymal stem cells (dBMMSCs) in comparison with the expression of the same proteins in dog periodontal fibroblasts (dPLFs).

DESIGN

dBMMSCs from the iliac crest were cultivated in Dulbecco's Modified Eagle's Medium (DMEM). Flow cytometry analysis (FCA) was used to characterize dBMMSC. Cells were stimulated with bFGF (1, 5 and 10 ng/mL) after 24 and 48 h. Real time RT-PCR was performed to verify collagen type I and fibronectin expressions. MTT assay was used to confirm cellular proliferation. Statistical analyses were performed (ANOVA and Kruskal-Wallis tests; p<0.05).

RESULTS

FCA showed 55.98% of CD34+ and 32.67% of CD90+ after bone marrow aspiration; 3.33% of CD34+ and 33.0% of CD90+ before P1. After P2, 10.54% of dBMMSCs expressed CD90, whereas after P3, this number decreased to 1.58%. dPLFs presented 4.04% of CD90+ and 1.05% of CD34+ after P3. MTT evaluation showed increase in dBMSC proliferation with 5 ng/mL bFGF-stimulus after 24-h. Both collagen I and fibronectin expression were very similar between the two cells groups after 24-h stimulation with 1 ng/mL bFGF concentration. Fibronectin and collagen I expressions were higher after 24-h stimulation with 5 ng/mL bFGF.

CONCLUSION

dBMMSCs (1 ng/mL-bFGF stimulus after 24 h) are very similar to dPLFs as regards morphological and immunostaining characteristics, and collagen and/or fibronectin production. The dBMMSCs presented the highest protein expression rates with 5 ng/mL-bFGF stimulus after 24-h.

The combination of mesenchymal stem cells and a bone scaffold in the treatment of vertebral body defects

PURPOSE

Vertebral body defects represent one of the most common orthopedic challenges. In order to advance the transfer of stem cell therapies into orthopedic clinical practice, we performed this study to evaluate the safety and efficacy of a composite bioartificial graft based on a hydroxyapatite bone scaffold (CEM-OSTETIC(®)) combined with human mesenchymal stem cells (MSCs) in a rat model of vertebral body defects.

METHODS

Under general isoflurane anesthesia, a defect in the body of the L2 vertebra was prepared and left to heal spontaneously (group 1), implanted with scaffold material alone (group 2), or implanted with a scaffold together with 0.5 million MSCs (group 3) or 5 million MSCs (group 4). The rats were killed 8 weeks after surgery. Histological and histomorphometrical evaluation of the implant as well as micro-CT imaging of the vertebrae were performed.

RESULTS

We observed a significant effect on the formation of new bone tissue in the defect in group 4 when compared to the other groups and a reduced inflammatory reaction in both groups receiving a scaffold and MSCs. We did not detect any substantial pathological changes or tumor formation after graft implantation.

CONCLUSIONS

MSCs in combination with a hydroxyapatite scaffold improved the repair of a model bone defect and might represent a safe and effective alternative in the treatment of vertebral bone defects.