Bone Regeneration of Canine Peri-implant Defects Using Cell Sheets of Adipose-Derived Mesenchymal Stem Cells and Platelet-Rich Fibrin Membranes

The Use of Mesenchymal Stromal/Stem Cells (MSC) for Periodontal and Peri-implant Regeneration: Scoping Review

The necessity for regenerating peri-implant and periodontal tissues is increasingly apparent. Periodontal diseases can result in a significant loss of clinical attachment level, and tissue regeneration stands as the ultimate goal of periodontal therapy. With the rise of osseointegration, the prosthetic rehabilitation of missing teeth using dental implants has surged, leading to a frequent need for alveolar bone regeneration around implants. This review assessed studies reporting various sources of mesenchymal stromal/stem cells (MSC) and their potential in regenerating periodontal and peri-implant bone tissue. A search was conducted across seven databases spanning the past decade. Three authors independently screened all identified titles and abstracts for eligibility, generating tables to summarize included studies in animals and humans separately. A total of 55 articles were chosen for final evaluation, showcasing five origins of MSC used in humans and animals for regenerating periodontal tissues and peri-implant bone, using different types of scaffolds. Overall, research from the past decades supports the effectiveness of MSC in promoting periodontal and peri-implant regeneration. However, the impact of MSC on regenerative therapies in humans is still in its initial stages. Future research should optimize MSC application protocols by combining techniques, such as the use of nanomedicine and 3D printing for tissue engineering. Clinical studies should also understand the long-term effects and compare MSC therapies with current treatment modalities. By addressing these areas, the scientific community can ensure that MSC therapies are both safe and effective, ultimately enhancing therapeutic strategies and treatment outcomes in Periodontology and Implantology.

Endogenous Tissue Engineering for Chondral and Osteochondral Regeneration: Strategies and Mechanisms

Increasing attention has been paid to the development of effective strategies for articular cartilage (AC) and osteochondral (OC) regeneration due to their limited self-reparative capacities and the shortage of timely and appropriate clinical treatments. Traditional cell-dependent tissue engineering faces various challenges such as restricted cell sources, phenotypic alterations, and immune rejection. In contrast, endogenous tissue engineering represents a promising alternative, leveraging acellular biomaterials to guide endogenous cells to the injury site and stimulate their intrinsic regenerative potential. This review provides a comprehensive overview of recent advancements in endogenous tissue engineering strategies for AC and OC regeneration, with a focus on the tissue engineering triad comprising endogenous stem/progenitor cells (ESPCs), scaffolds, and biomolecules. Multiple types of ESPCs present within the AC and OC microenvironment, including bone marrow-derived mesenchymal stem cells (BMSCs), adipose-derived mesenchymal stem cells (AD-MSCs), synovial membrane-derived mesenchymal stem cells (SM-MSCs), and AC-derived stem/progenitor cells (CSPCs), exhibit the ability to migrate toward injury sites and demonstrate pro-regenerative properties. The fabrication and characteristics of scaffolds in various formats including hydrogels, porous sponges, electrospun fibers, particles, films, multilayer scaffolds, bioceramics, and bioglass, highlighting their suitability for AC and OC repair, are systemically summarized. Furthermore, the review emphasizes the pivotal role of biomolecules in facilitating ESPCs migration, adhesion, chondrogenesis, osteogenesis, as well as regulating inflammation, aging, and hypertrophy-critical processes for endogenous AC and OC regeneration. Insights into the applications of endogenous tissue engineering strategies for in vivo AC and OC regeneration are provided along with a discussion on future perspectives to enhance regenerative outcomes.

Mesenchymal Stem Cell-based Scaffolds in Regenerative Medicine of Dental Diseases

Biomedical engineering breakthroughs and increased patient expectations and requests for more comprehensive care are propelling the field of regenerative dentistry forward at a fast pace. Stem cells (SCs), bioactive compounds, and scaffolds are the mainstays of tissue engineering, the backbone of regenerative dentistry. Repairing damaged teeth and gums is a significant scientific problem at present. Novel therapeutic approaches for tooth and periodontal healing have been inspired by tissue engineering based on mesenchymal stem cells (MSCs). Furthermore, as a component of the MSC secretome, extracellular vesicles (EVs) have been shown to contribute to periodontal tissue repair and regeneration. The scaffold, made of an artificial extracellular matrix (ECM), acts as a supporting structure for new cell development and tissue formation. To effectively promote cell development, a scaffold must be non-toxic, biodegradable, biologically compatible, low in immunogenicity, and safe. Due to its promising biological characteristics for cell regeneration, dental tissue engineering has recently received much attention for its use of natural or synthetic polymer scaffolds with excellent mechanical properties, such as small pore size and a high surface-to-volume ratio, as a matrix. Moreover, as a bioactive material for carrying MSC-EVs, the combined application of scaffolds and MSC-EVs has a better regenerative effect on dental diseases. In this paper, we discuss how MSCs and MSC-derived EV treatment may be used to regenerate damaged teeth, and we highlight the role of various scaffolds in this process.

Osseointegration Potential Assessment of Bone Graft Materials Loaded with Mesenchymal Stem Cells in Peri-Implant Bone Defects

Many studies have been exploring the use of bone graft materials (BGMs) and mesenchymal stem cells in bone defect reconstruction. However, the regeneration potential of Algipore (highly purified hydroxyapatite) and Biphasic (hydroxyapatite/beta-tricalcium phosphate) BGMs combined with bone marrow-derived mesenchymal stem cells (BMSCs) remains unclear. Therefore, we evaluated their osseointegration capacities in reconstructing peri-implant bone defects. The cellular characteristics of BMSCs and the material properties of Algipore and Biphasic were assessed in vitro. Four experimental groups-Algipore, Biphasic, Algipore+BMSCs, and Biphasic+BMSCs-were designed in a rabbit tibia peri-implant defect model. Implant stability parameters were measured. After 4 and 8 weeks of healing, all samples were evaluated using micro-CT, histological, and histomorphometric analysis. In the energy-dispersive X-ray spectroscopy experiment, the Ca/P ratio was higher for Algipore (1.67) than for Biphasic (1.44). The ISQ values continuously increased, and the PTV values gradually decreased for all groups during the healing period. Both Algipore and Biphasic BGM promoted new bone regeneration. Higher implant stability and bone volume density were observed when Algipore and Biphasic BGMs were combined with BMSCs. Biphasic BGM exhibited a faster degradation rate than Algipore BGM. Notably, after eight weeks of healing, Algipore with BSMCs showed more bone-implant contact than Biphasic alone (p < 0.05). Both Algipore and Biphasic are efficient in reconstructing peri-implant bone defects. In addition, Algipore BGM incorporation with BSMCs displayed the best performance in enhancing implant stability and osseointegration potential.

Advanced Platelet-Rich Fibrin Extract Treatment Promotes the Proliferation and Differentiation of Human Adipose-Derived Mesenchymal Stem Cells through Activation of Tryptophan Metabolism

BACKGROUND

Advanced platelet-rich fibrin extract (APRFE) contains a high concentration of various cytokines that are helpful for improving stem cells repair function.

OBJECTIVE

However, the underlying mechanism of APRFE improving stem cell repairing is not clear.

METHODS

We produced APRFE by centrifuging fresh peripheral blood samples and isolated and identified human adipose-derived mesenchymal stem cells (ADMSCs). The abundance of cytokines contained in APRFE was detected by the Enzyme-linked immunosorbent assay (ELISA). The ADMSCs treated with or without APRFE were collected for transcriptome sequencing.

RESULTS

Based on the sequencing data, the expression profiles were contracted. The differentially expressed genes and lncRNA (DEGs and DElncRNAs) were obtained using for the differential expression analysis. The lncRNA-miRNA-mRNA network was constructed based on the miRNet database. The further enrichment analysis results showed that the biological functions were mainly related to proliferation, differentiation, and cell-cell function. To explore the role of APRFE, the protein-protein interaction network was constructed among the cytokines included in APRFE and DEGs. Furthermore, we constructed the global regulatory network based on the RNAInter and TRRUST database. The pathways in the global regulatory network were considered as the core pathways. We found that the DEGs in the core pathways were associated with stemness scores.

CONCLUSION

In summary, we predicted that APRFE activated three pathways (tryptophan metabolism, mTOR signaling pathway, and adipocytokine signaling) to promote the proliferation and differentiation of ADMSCs. The finding may be helpful for guiding the application of ADMSCs in the clinic.

Cell Sheet Technology as an Engineering-Based Approach to Bone Regeneration

Bone defects that are congenital or the result of infection, malignancy, or trauma represent a challenge to the global healthcare system. To address this issue, multiple research groups have been developing novel cell sheet technology (CST)-based approaches to promote bone regeneration. These methods hold promise for use in regenerative medicine because they preserve cell-cell contacts, cell-extracellular matrix interactions, and the protein makeup of cell membranes. This review introduces the concept and preparation system of the cell sheet (CS), explores the application of CST in bone regeneration, highlights the current states of the bone regeneration via CST, and offers perspectives on the challenges and future research direction of translating current knowledge from the lab to the clinic.

Current applications of adipose-derived mesenchymal stem cells in bone repair and regeneration: A review of cell experiments, animal models, and clinical trials

In the field of orthopaedics, bone defects caused by severe trauma, infection, tumor resection, and skeletal abnormalities are very common. However, due to the lengthy and painful process of related surgery, people intend to shorten the recovery period and reduce the risk of rejection; as a result, more attention is being paid to bone regeneration with mesenchymal stromal cells, one of which is the adipose-derived mesenchymal stem cells (ASCs) from adipose tissue. After continuous subculture and cryopreservation, ASCs still have the potential for multidirectional differentiation. They can be implanted in the human body to promote bone repair after induction in vitro, solve the problems of scarce sources and large damage, and are expected to be used in the treatment of bone defects and non-union fractures. However, the diversity of its differentiation lineage and the lack of bone formation potential limit its current applications in bone disease. Here, we concluded the current applications of ASCs in bone repair, especially with the combination and use of physical and biological methods. ASCs alone have been proved to contribute to the repair of bone damage in vivo and in vitro. Attaching to bone scaffolds or adding bioactive molecules can enhance the formation of the bone matrix. Moreover, we further evaluated the efficiency of ASC-committed differentiation in the bone in conditions of cell experiments, animal models, and clinical trials. The results show that ASCs in combination with synthetic bone grafts and biomaterials may affect the regeneration, augmentation, and vascularization of bone defects on bone healing. The specific conclusion of different materials applied with ASCs may vary. It has been confirmed to benefit osteogenesis by regulating osteogenic signaling pathways and gene transduction. Exosomes secreted by ASCs also play an important role in osteogenesis. This review will illustrate the understanding of scientists and clinicians of the enormous promise of ASCs’ current applications and future development in bone repair and regeneration, and provide an incentive for superior employment of such strategies.

Exendin-4 enhances osteogenic differentiation of adipose tissue mesenchymal stem cells through the receptor activator of nuclear factor-kappa B and osteoprotegerin signaling pathway

The capability of mesenchymal stem cells (MSCs) to repair bone damage and defects has long been investigated. The receptor activator of nuclear factor-kappa B (RANK), its ligand (RANKL) and the decoy receptor osteoprotegerin (OPG) axis is crucial to keep the equilibrium between osteoblastic and osteoclastic activity. Exendin-4 utilization increased bone formation and enhanced bone integrity. This study aimed to investigate the mentioned axis and determine the effect of exendin-4 upon adipose mesenchymal stem cells (Ad-MSCs) osteogenic differentiation. Ad-MSCs were isolated from rat epididymal fat, followed by characterization and then differentiation into osteocytes both in the presence or absence of exendin-4. Osteogenic differentiation was evaluated by alizarin red staining and the expression of osteogenic markers; using reverse transcriptase-quantitative polymerase chain reaction, western blotting and enzyme-linked immunoassay. MSCs derived from rat epididymal fat were isolated and characterized, along with their differentiation into osteocytes. The differentiated cells were alizarin red-stained, showing increased staining intensity upon addition of exendin-4. Moreover, the addition of exendin-4 elevated the messenger RNA expression levels of osteogenic markers; runt-related transcription factor-2 (RUNX-2), osteocalcin, and forkhead box protein O-1 while reducing the expression of the adipogenic marker peroxisome-proliferator-activated receptor-gamma. Exendin-4 addition elevated OPG levels in the supernatant of osteogenic differentiated cells. Moreover, exendin-4 elevated the protein levels of glucagon-like peptide-1 receptor and RUNX-2, while decreasing both RANK and RANKL. In conclusion, osteogenic differentiation of Ad-MSCs is associated with increased osteoblastic rather than osteoclastic activity. The findings of this study suggest that exendin-4 can enhance Ad-MSCs osteogenic differentiation partially through the RANK/RANKL/OPG axis.

Emerging treatment strategies in wound care

Wound healing is a complex process in tissue regeneration through which the body responds to the dissipated cells as a result of any kind of severe injury. Diabetic and non-healing wounds are considered an unmet clinical need. Currently, different strategic approaches are widely used in the treatment of acute and chronic wounds which include, but are not limited to, tissue transplantation, cell therapy and wound dressings, and the use of an instrument. A large number of literatures have been published on this topic; however, the most effective clinical treatment remains a challenge. The wound dressing involves the use of a scaffold, usually using biomaterials for the delivery of medication, autologous stem cells, or growth factors from the blood. Antibacterial and anti-inflammatory drugs are also used to stop the infection as well as accelerate wound healing. With an increase in the ageing population leading to diabetes and associated cutaneous wounds, there is a great need to improve the current treatment strategies. This research critically reviews the current advancement in the therapeutic and clinical approaches for wound healing and tissue regeneration. The results of recent clinical trials suggest that the use of modern dressings and skin substitutes is the easiest, most accessible, and most cost-effective way to treat chronic wounds with advances in materials science such as graphene as 3D scaffold and biomolecules hold significant promise. The annual market value for successful wound treatment exceeds over $50 billion US dollars, and this will encourage industries as well as academics to investigate the application of emerging smart materials for modern dressings and skin substitutes for wound therapy.

Stem cells in tendon regeneration and factors governing tenogenesis

Tendons are connective tissue structures of paramount importance to the human ability of locomotion. Tendinopathy and tendon rupture can be resistant to treatment and often recurs, thus resulting in a significant health problem with a relevant social impact worldwide. Unfortunately, existing treatment approaches are suboptimal. A better understanding of the basic biology of tendons may provide a better way to solve these problems and promote tendon regeneration. Stem cells, either obtained from tendons or non-tendon sources, such as bone marrow (BMSCs), adipose tissue (AMSCs), as well as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have received increasing attention toward enhancing tendon healing. There are many studies showing that stem cells can contribute to improving tendon healing. Hence, in this review, the current knowledge of BMSCs, AMSCs, TSPCs, ESCs and iPSCs for tendon regeneration, as well as the advantages and limitations among them, has been highlighted. Moreover, the transcriptional and bioactive factors governing tendon healing processes have been discussed.

The therapeutic potential of mesenchymal stem cells in treating osteoporosis

Osteoporosis (OP), a common systemic metabolic bone disease, is characterized by low bone mass, increasing bone fragility and a high risk of fracture. At present, the clinical treatment of OP mainly involves anti-bone resorption drugs and anabolic agents for bone, but their long-term use can cause serious side effects. The development of stem cell therapy and regenerative medicine has provided a new approach to the clinical treatment of various diseases, even with a hope for cure. Recently, the therapeutic advantages of the therapy have been shown for a variety of orthopedic diseases. However, these stem cell-based researches are currently limited to animal models; the uncertainty regarding the post-transplantation fate of stem cells and their safety in recipients has largely restricted the development of human clinical trials. Nevertheless, the feasibility of mesenchymal stem cells to treat osteoporotic mice has drawn a growing amount of intriguing attention from clinicians to its potential of applying the stem cell-based therapy as a new therapeutic approach to OP in the future clinic. In the current review, therefore, we explored the potential use of mesenchymal stem cells in human OP treatment.

The Combined Use of Platelet-Rich Plasma and Adipose-Derived Mesenchymal Stem Cells Promotes Healing. A Review of Experimental Models and Future Perspectives

Wound healing and tissue regeneration are a field of clinical medicine presenting high research interest, since various local and systematic factors can inhibit these processes and lead to an inferior result. New methods of healing enhancement constantly arise, which, however, require experimental validation before their establishment in everyday practice. Platelet-rich plasma (PRP) is a well-known autologous factor that promotes tissue healing in various surgical defects. PRP derives from the centrifugation of peripheral blood and has a high concentration of growth factors that promote healing. Recently, the use of adipose-derived mesenchymal stem cells (ADMSCs) has been thoroughly investigated as a form of wound healing enhancement. ADMSCs are autologous stem cells deriving from fat tissue, with a capability of differentiation in specific cells, depending on the micro-environment that they are exposed to. The aim of the present comprehensive review is to record the experimental studies that have been published and investigate the synergistic use of PRP and ADMSC in animal models. The technical aspects of experimentations, as well as the major results of each study, are discussed. In addition, the limited clinical studies including humans are also reported. Future perspectives are discussed, along with the limitations of current studies on the long-term follow up needed on efficacy and safety.

Platelet-rich fibrin-loaded PCL/chitosan core-shell fibers scaffold for enhanced osteogenic differentiation of mesenchymal stem cells

Here, we fabricated the platelet-rich fibrin (PRF)-loaded PCL/chitosan (PCL/CS-PRF) core-shell nanofibrous scaffold through a coaxial electrospinning method. Our goal was to evaluate the effect of CS-RPF in the core layer of the nanofibrous on the osteogenic differentiation of human mesenchymal stem cells (HMSCs). The elastic modulus of PCL/CS-PRF core-shell scaffold (44 MPa) was about 1.5-fold of PCL/CS scaffold (25 MPa). The specific surface area of the scaffolds increased from 9.98 m²/g for PCL/CS scaffold to 16.66 m²/g for the PCL/CS-PRF core-shell nanofibrous scaffold. Moreover, the release rate of PRF from PCL/CS-PRF nanofibrous scaffold was measured to be 24.50% after 10 days which showed slow and sustained release of PRF from the nanofibrous. The formation of Ca-P on the surface of scaffold immersed in simulated body fluid solution indicated the suitable osteoconductivity of PCL/CS-PRF core-shell nanofibrous scaffold. Also, the value of ALP activity and calcium deposited on the surface of PCL/CS-PRF core-shell nanofibrous scaffold were 81.97 U/L and 40.33 μg/scaffold, respectively after 14 days, which confirmed the significantly higher amounts of ALP and calcium deposition on the scaffold containing PRF compared to PCL/CS scaffold. Due to higher hydrophilicity and porosity of PCL/CS-PRF core-shell nanofibrous scaffold compared to PCL/CS scaffold, a better bone cell growth on surface of PCL/CS-PRF scaffold was observed. The Alizarin red-positive area was significantly higher on PCL/CS-PRF scaffold compared to PCL/CS scaffold, indicating more calcium deposition and osteogenic differentiation of HMSCs in the presence of PRF. Our findings demonstrate that PCL/CS-PRF core-shell scaffolds can provide a strong construct with improved osteogenic for bone tissue engineering applications.

Injectable platelet-rich fibrin influences the behavior of gingival mesenchymal stem cells

In this study, we examined the effects of injectable platelet-rich fibrin (iPRF) on proliferation and osteodifferentiation in mesenchymal stem cells (MSCs) isolated from human gingiva. Gingival MSCs (gMSCs) were grown in experimental culture media with different concentrations of iPRF [5%, 10%, and replacement of fetal calf serum (FCS) in the standard media with 10% iPRF–10% iPRF-FCS]. Immunophenotyping of gMSCs was performed after seven days by flow cytometry, and their proliferation was examined after three and seven days using the Cell Counting Kit-8 method. After 14 days in culture, spontaneous osteogenic differentiation of gMSCs was evaluated via real-time polymerase chain reaction. All gMSCs were positive for cluster of differentiation (CD) 105, CD73, CD90, and CD44, and negative for CD34/45, CD14, CD79a, and human leukocyte antigen, DR isotype (HLA-DR). Reduced expression of some surface antigens was observed in the gMSCs grown in 10% iPRF-FCS medium compared to the other groups. After three days, gMSCs grown in 10% iPRF had proliferated significantly less than the other groups. After seven days, proliferation was significantly higher in the 5% iPRF cells compared to the control, while proliferation in the 10% iPRF and 10% iPRF-FCS groups was significantly lower. No spontaneous osteogenic differentiation was observed in the presence of iPRF, as observed by low runt-related transcription factor 2 (RUNX2) expression. Some expression of secreted protein acidic and cysteine rich (SPARC) and collagen 1 alpha (COL1A) was observed for all the gMSCs regardless of the culture medium composition. gMSCs grown in 10% iPRF had significantly lower SPARC expression. In conclusion, 5% iPRF stimulated gMSC proliferation, and an excessively high concentration of iPRF can impair osteogenic induction.

Application of Adipose Tissue Stem Cells in Regenerative Dentistry: A Systematic Review

AIM

The aim of this study was to systematically review the applications of adipose tissue stem cells (ADSCs) in regenerative dentistry.

MATERIALS AND METHODS

An electronic search was conducted in Medline (PubMed) and Scopus databases. The original research associated with the role of ADSCs in regeneration of alveolar bone, periodontal ligament (PDL), cementum as well as the dental pulp was evaluated. Among the included studies, three animal studies and one human study had low risk of bias.

RESULTS

A total of 33 relevant studies were included in the review. The animal models, in vivo human, and in vitro studies revealed that ADSCs had a significant osteogenic differentiation potential. Besides, they had potential to differentiate into PDL, cementum, and dental pulp tissue.

CONCLUSION

The ADSCs may be specifically applied for bone tissue engineering in the management of alveolar bone defects, specifically in dental implants and periodontal disease. However, their role in regeneration of PDL, cementum, and dental pulp requires further investigations. Overall, their applications in regenerative dentistry needs further verification through human clinical trials.

Co-culture with Endothelial Progenitor Cells promotes the Osteogenesis of Bone Mesenchymal Stem Cells via the VEGF-YAP axis in high-glucose environments

Patients with type 2 diabetes mellitus (T2DM) have a high risk of fracture and experience poor bone healing. In recent years, bone mesenchymal stem cells (BMSCs) and endothelial progenitor cells (EPCs) have become the most commonly used cells in cell therapy and tissue engineering. In this study, we found that high glucose levels had a negative effect on the differentiation of BMSCs and EPCs. Considering that EPCs-BMSCs sheets can provide endothelial cells and osteoblastic cells, we transplanted cell sheets into T2DM rats with bilateral skull defects. The outcomes of the in vivo study revealed that EPCs-BMSCs sheets promoted ossification, which was verified by micro-CT and immunohistochemistry (IHC) analyses. Furthermore, we detected the VEGF content in the culture supernatant using an enzyme-linked immunosorbent assay (ELISA). The results showed that the BMSCs co-cultured with EPCs presented a higher level of VEGF than other cells. To assess the differentiation and migration of BMSCs exposed to VEGF, ALP staining, scratch assay and qRT-PCR analysis were performed. In addition, we used immunofluorescence and western blotting analysis to further explore the related mechanisms. The results showed that cells cultured with VEGF had a stronger actin cytoskeleton and a greater amount of nuclear and total YAP than cells cultured without VEGF. Taken together, our results indicate that co-culture with EPCs could promote the osteogenesis of BMSCs partially via VEGF. Furthermore, YAP and F-actin play important roles in this process.

In Vitro Cultures of Adipose-Derived Stem Cells: An Overview of Methods, Molecular Analyses, and Clinical Applications

Adipose-derived stem cells (ASCs) exhibiting mesenchymal stem cell (MSC) characteristics, have been extensively studied in recent years. Because they have been shown to differentiate into lineages such as osteogenic, chondrogenic, neurogenic or myogenic, the focus of most of the current research concerns either their potential to replace bone marrow as a readily available and abundant source of MSCs, or to employ them in regenerative and reconstructive medicine. There is close to consensus regarding the methodology used for ASC isolation and culture, whereas a number of molecular analyses implicates them in potential therapies of a number of pathologies. When it comes to clinical application, there is a range of examples of animal trials and clinical studies employing ASCs, further emphasizing the advancement of studies leading to their more widespread use. Nevertheless, in vitro studies will most likely continue to play a significant role in ASC studies, both providing the molecular knowledge of their ex vivo properties and possibly serving as an important step in purification and application of those cells in a clinical setting. Therefore, it is important to consider current methods of ASC isolation, culture, and processing. Furthermore, molecular analyses and cell surface properties of ASCs are essential for animal studies, clinical studies, and therapeutic applications of the MSC properties.

Doxycycline and Zinc Loaded Silica-Nanofibrous Polymers as Biomaterials for Bone Regeneration

The main target of bone tissue engineering is to design biomaterials that support bone regeneration and vascularization. Nanostructured membranes of (MMA)₁-co-(HEMA)₁/(MA)₃-co-(HEA)₂ loaded with 5% wt of SiO₂-nanoparticles (HOOC-Si-Membrane) were doped with zinc (Zn-HOOC-Si-Membrane) or doxycycline (Dox-HOOC-Si-Membrane). Critical bone defects were effectuated on six New Zealand-bred rabbit skulls and covered with the membranes. After six weeks, the bone architecture was evaluated with micro computed tomography. Three histological analyses were utilized to analyse bone regeneration, including von Kossa silver nitrate, toluidine blue and fluorescence. All membrane-treated defects exhibited higher number of osteocytes and bone perimeter than the control group without the membrane. Zn-HOOC-Si-Membranes induced higher new bone and osteoid area than those treated with HOOC-Si-Membranes, and control group, respectively. Zn-HOOC-Si-Membranes and Dox-HOOC-Si-Membranes attained the lowest ratio M1 macrophages/M2 macrophages. Dox-HOOC-Si-Membranes caused the lowest number of osteoclasts, and bone density. At the trabecular new bone, Zn-HOOC-Si-Membranes produced the highest angiogenesis, bone thickness, connectivity, junctions and branches. Zn-HOOC-Si-Membranes enhanced biological activity, attained a balanced remodeling, and achieved the greatest regenerative efficiency after osteogenesis and angiogenesis assessments. The bone-integrated Zn-HOOC-Si-Membranes can be considered as bioactive modulators provoking a M2 macrophages (pro-healing cells) increase, being a potential biomaterial for promoting bone repair.

Application of Nanomaterials in Regulating the Fate of Adipose-derived Stem Cells

Adipose-derived stem cells are adult stem cells which are easy to obtain and multi-potent. Stem-cell therapy has become a promising new treatment for many diseases, and plays an increasingly important role in the field of tissue repair, regeneration and reconstruction. The physicochemical properties of the extracellular microenvironment contribute to the regulation of the fate of stem cells. Nanomaterials have stable particle size, large specific surface area and good biocompatibility, which has led them being recognized as having broad application prospects in the field of biomedicine. In this paper, we review recent developments of nanomaterials in adipose-derived stem cell research. Taken together, the current literature indicates that nanomaterials can regulate the proliferation and differentiation of adipose-derived stem cells. However, the properties and regulatory effects of nanomaterials can vary widely depending on their composition. This review aims to provide a comprehensive guide for future stem-cell research on the use of nanomaterials.

Allogenic Bone Graft Enriched by Periosteal Stem Cell and Growth Factors for Osteogenesis in Critical Size Bone Defect in Rabbit Model: Histopathological and Radiological Evaluation

Background & Objective:

This study aimed to investigate the effect of decellularized allogeneic bone graft enriched by periosteal stem cells (PSCs) and growth factors on the bone repair process in a rabbit model, which could be used in many orthopedic procedures.

Methods:

In this experimental study, a critical size defect (CSD) (10 mm) was created in the radial diaphysis of 40 rabbits. In group A, the defect was left intact with no medical intervention. In group B, the defect was filled by a decellularized bone graft. In group C, the defect was implanted by a decellularized bone graft enriched with platelet growth factors. In group D, the defect was treated by a decellularized bone graft seeded by periosteal mesenchymal stem cells (MSCs). Also, in group E, the defect was filled by a decellularized bone graft enriched with platelet growth factors and periosteal MSCs. Radiological evaluation was done on the first day and then in the second, fourth, and eighth weeks after the operation. The specimens were harvested on the 28th and 56th postoperative days and evaluated for histopathological criteria.

Results:

The radiologic and microscopic analysis of the healing process in bone defects of the treated groups (C, D, and E) revealed more advanced repair criteria than those of groups A and B significantly (P<0.05).

Conclusion:

Based on this study, it appears that implantation of concentrated PSCs in combination with growth factors and allogeneic cortical bone graft is an effective therapy for the repair of large bone defects.

Human Stem Cell Responses and Surface Characteristics of 3D Printing Co-Cr Dental Material

Recently, the selective laser melting (SLM) method of manufacturing three dimensional (3D) dental prosthetics by applying a laser to metal powder has been widely used in the field of dentistry. This study investigated human adipose derived stem cell (hADSC) behavior on a 3D printed cobalt-chrome (Co-Cr) alloy and its surface characteristics and compared them those of a nickel-chrome (Ni-Cr) alloy. Alloys were divided into four groups according to the material and manufacturing methods. Co-Cr disks were manufactured with three different methods: a conventional casting method, a metal milling method, and an SLM method. Ni-Cr disks were manufactured with a conventional casting method. The surface roughness and compositions of the disks were assessed. hADSCs were then cultured on the disks. Cell morphologies on the disks were analyzed by a field emission scanning electron microscope (FE-SEM). Cell proliferation was assessed with a bromodeoxyuridine (BrdU) assay kit. Cell viability was evaluated with a water-soluble tetrazolium salt (WST) assay kit. There were no differences in surface roughness between all groups. The cells were well attached to the disks, and morphologies of the cells were similar. The cell proliferation and viability of the Ni-Cr disks were significantly lower than the other groups. However, the Co-Cr disks showed no differences in their different fabricating methods. In conclusion, the biocompatibility of 3D printed Co-Cr alloys showed comparable results compared to that of the conventional casting method, and these alloys were more biocompatible than Ni-Cr alloys.

The Potential of Different Origin Stem Cells in Modulating Oral Bone Regeneration Processes

Tissue engineering has gained much momentum since the implementation of stem cell isolation and manipulation for regenerative purposes. Despite significant technical improvements, researchers still have to decide which strategy (which type of stem cell) is the most suitable for their specific purpose. Therefore, this short review discusses the advantages and disadvantages of the three main categories of stem cells: embryonic stem cells, mesenchymal stem cells and induced pluripotent stem cells in the context of bone regeneration for dentistry-associated conditions. Importantly, when deciding upon the right strategy, the selection needs to be made in concordance with the morbidity and the life-threatening level of the condition in discussion. Therefore, even when a specific type of stem cell holds several advantages over others, their availability, invasiveness of the collection method and ethical standards become deciding parameters.