The effect of surface treatment of titanium with sand-blasting/acid-etching or hydroxyapatite-coating and application of bone morphogenetic protein-2 on attachment, proliferation, and differentiation of stem cells derived from buccal fat pad

Biomaterials and Adipose-Derived Mesenchymal Stem Cells for Regenerative Medicine: A Systematic Review

The use of biological templates for the suitable growth of adipose-derived mesenchymal stem cells (AD-MSC) and “neo-tissue” construction has exponentially increased over the last years. The bioengineered scaffolds still have a prominent and biocompatible framework playing a role in tissue regeneration. In order to supply AD-MSCs, biomaterials, as the stem cell niche, are more often supplemented by or stimulate molecular signals that allow differentiation events into several strains, besides their secretion of cytokines and effects of immunomodulation. This systematic review aims to highlight the details of the integration of several types of biomaterials used in association with AD-MSCs, collecting notorious and basic data of in vitro and in vivo assays, taking into account the relevance of the interference of the cell lineage origin and handling cell line protocols for both the replacement and repairing of damaged tissues or organs in clinical application. Our group analyzed the quality and results of the 98 articles selected from PubMed, Scopus and Web of Science. A total of 97% of the articles retrieved demonstrated the potential in clinical applications. The synthetic polymers were the most used biomaterials associated with AD-MSCs and almost half of the selected articles were applied on bone regeneration.

Combining Sandblasting, Alkaline Etching, and Collagen Immobilization to Promote Cell Growth on Biomedical Titanium Implants

Our objective in this study was to promote the growth of bone cells on biomedical titanium (Ti) implant surfaces via surface modification involving sandblasting, alkaline etching, and type I collagen immobilization using the natural cross-linker genipin. The resulting surface was characterized in terms topography, roughness, wettability, and functional groups, respectively using field emission scanning electron microscopy, 3D profilometry, and attenuated total reflection-Fourier transform infrared spectroscopy. We then evaluated the adhesion, proliferation, initial differentiation, and mineralization of human bone marrow mesenchymal stem cells (hMSCs). Results show that sandblasting treatment greatly enhanced surface roughness to promote cell adhesion and proliferation and that the immobilization of type I collagen using genipin enhanced initial cell differentiation as well as mineralization in the extracellular matrix of hMSCs. Interestingly, the nano/submicro-scale pore network and/or hydrophilic features on sandblasted rough Ti surfaces were insufficient to promote cell growth. However, the combination of all proposed surface treatments produced ideal surface characteristics suited to Ti implant applications.

Comparing the effects of Elaegnus Angustifolia, Hypericum Perforatum and Psidium Guajava extracts on metabolic activity of dental pulp-derived mesenchymal stem cells

Dental pulp derived-mesenchymal stem cells (DP-MSCs) is considered a suitable are candidate for tissue engineering techniques and osseous reconstruction. Based on the hypothesis that Hypericum perforatum, Elaeagnus Angustifolia and Psidium guajava extracts can be used in cell-based bone tissue engineering due to meagre cytotoxicity response in the cell culture medium, their effects on the viability and metabolic activity of DP-MSCs were investigated and compared with each extract. DP-MSCs were extracted from human dental pulp, characterized by flow cytometry, and differentiated into Osteogenic and adipogenic lineages which were then cultured in different concentrations of E. Angustifolia, H. perforatum and P. guajava extracts at different time intervals followed by MTT assay evaluation. The dental pulp mesenchymal stem cells were evaluated for their plastic adherence ability, fibroblast-like and spindle morphology. According to flow cytometry data, isolated cells from DP-MSCs expressed MSCs markers. A comparison of herbal extracts' concentrations revealed that 500 μg/ml was toxic to dental pulp stem cells, a guide to the toxic dose for DP-MSCs. The P.guajava bore low toxicity and increased dental pulp stem cell viability in comparison to the other two herbal extracts. The hydro-alcoholic extracts of E. Angustifolia, H. perforatum, and P. guajava were efficient in DP-MSCs viability, and therefore were concluded to be useful in maintaining structural and functional cell viability. It was also concluded that the co-culture of stem cells with herbal elements could stimulate endogenous factors to enhance the proliferation and viability of MSCs.

Fabrication and characterization of novel ethyl cellulose-grafted-poly (ɛ-caprolactone)/alginate nanofibrous/macroporous scaffolds incorporated with nano-hydroxyapatite for bone tissue engineering

The major challenge of tissue regeneration is to develop three dimensional scaffolds with suitable properties which would mimic the natural extracellular matrix to induce the adhesion, proliferation, and differentiation of cells. Several materials have been used for the preparation of the scaffolds for bone regeneration. In this study, novel ethyl cellulose-grafted-poly (ɛ-caprolactone) (EC-g-PCL)/alginate scaffolds with different contents of nano-hydroxyapatite were prepared by combining electrospinning and freeze-drying methods in order to provide nanofibrous/macroporous structures with good mechanical properties. For this aim, EC-g-PCL nanofibers were obtained with electrospinning, embedded layer-by-layer in alginate solutions containing nano-hydroxyapatite particles, and finally, these constructions were freeze-dried. The scaffolds possess highly porous structures with interconnected pore network. The swelling, porosity, and degradation characteristics of the EC-g-PCL/alginate scaffolds were decreased with the increase in nano-hydroxyapatite contents, whereas increases in the in-vitro biomineralization and mechanical strength were observed as the nano-hydroxyapatite content was increased. The cell response to EC-g-PCL/alginate scaffolds with/or without nano-hydroxyapatite was investigated using human dental pulp stem cells (hDPSCs). hDPSCs displayed a high adhesion, proliferation, and differentiation on nano-hydroxyapatite-incorporated EC-g-PCL/alginate scaffolds compared to pristine EC-g-PCL/alginate scaffold. Overall, these results suggested that the EC-g-PCL/alginate-HA scaffolds might have potential applications in bone tissue engineering.

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.

Positron Annihilation and Complementary Studies of Copper Sandblasted with Alumina Particles at Different Pressures

Positron annihilation spectroscopy and complementary methods were used to detect changes induced by sandblasting of alumina particles at different pressures varying from 1 to 6 bar in pure well-annealed copper. The positron lifetime measurements revealed existence of dislocations and vacancy clusters in the adjoined surface layer. The presence of retained alumina particles in the copper at the depth below 50 µm was found in the SEM pictures and also in the annihilation line shape parameter profiles measured in the etching experiment. The profiles show us that the total depth of damaged zones induced by sandblasting of alumina particles ranges from 140 µm up to ca. 800 µm and it depends on the applied pressure. The work-hardening of the adjoined surface layer was found in the microhardness measurements at the cross-section of the sandblasted samples.

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.

Development of Novel Biocomposite Scaffold of Chitosan-Gelatin/Nanohydroxyapatite for Potential Bone Tissue Engineering Applications

In this study, a three-dimensional chitosan-gelatin/nanohydroxyapatite (ChG/nHaP) scaffold was successfully fabricated and characterized in terms of swelling, degradation, cell proliferation, cell attachment, and mineralization characterizations. The ChG/nHaP scaffold was fabricated with a mean pore size of 100-180 μm. Our results showed that the physicochemical and biological properties of the scaffolds were affected by the presence of HaP. The swelling and degradation characteristics of the ChG scaffold were remarkably decreased by the addition of HaP. On the other hand, the presence of HaP remarkably improved the MC3T3-E1 cell attachment and cell growth in the scaffold membrane. The biocompatible nature of the ChG/nHaP scaffold leads to the development of finely scaled mineral deposits on the scaffold membrane. Thus, HaP played an important role in improving the biological performance of the scaffold. Therefore, the ChG/nHaP scaffold could be applied as a suitable material for bone tissue engineering applications.

Fabrication and characterization of novel nano-biocomposite scaffold of chitosan-gelatin-alginate-hydroxyapatite for bone tissue engineering

A novel nano-biocomposite scaffold was fabricated in bead form by applying simple foaming method, using a combination of natural polymers-chitosan, gelatin, alginate and a bioceramic-nano-hydroxyapatite (nHAp). This approach of combining nHAp with natural polymers to fabricate the composite scaffold, can provide good mechanical strength and biological property mimicking natural bone. Environmental scanning electron microscopy (ESEM) images of the nano-biocomposite scaffold revealed the presence of interconnected pores, mostly spread over the whole surface of the scaffold. The nHAp particulates have covered the surface of the composite matrix and made the surface of the scaffold rougher. The scaffold has a porosity of 82% with a mean pore size of 112±19.0μm. Swelling and degradation studies of the scaffold showed that the scaffold possesses excellent properties of hydrophilicity and biodegradability. Short term mechanical testing of the scaffold does not reveal any rupturing after agitation under physiological conditions, which is an indicative of good mechanical stability of the scaffold. In vitro cell culture studies by seeding osteoblast cells over the composite scaffold showed good cell viability, proliferation rate, adhesion and maintenance of osteoblastic phenotype as indicated by MTT assay, ESEM of cell-scaffold construct, histological staining and gene expression studies, respectively. Thus, it could be stated that the nano-biocomposite scaffold of chitosan-gelatin-alginate-nHAp has the paramount importance for applications in bone tissue-engineering in future regenerative therapies.

Peptide aptamers: Novel coatings for orthopaedic implants

Current processes for coating titanium implants with ceramics involve very high energy techniques with associated high cost and disadvantages such as heterogeneity of the coatings, phase transformations and inability to coat complex structures. In order to address the above problems, we propose a biomimetic hydroxyapatite coating process with the use of peptides that can bind both on titanium surfaces and hydroxyapatite. The peptides enabled homogeneous coating of a titanium surface with hydroxyapatite. The hydroxyapatite-peptide sandwich coating showed no adverse effects on cell number or collagen deposition. This makes the sandwich coated titanium a good candidate for titanium implants used in orthopaedics and dentistry.

Evaluation of the effects of Angelicae dahuricae radix on the morphology and viability of mesenchymal stem cells

Angelicae dahuricae radix is a traditional herbal medicine used to treat various diseases in China and Korea, such as colds, headaches, rhinitis and psoriasis. Angelicae dahuricae radix has been used as an anti-inflammatory, analgesic, antipyretic and antioxidant remedy. This study was performed in order to evaluate the effects of the extracts of Angelicae dahuricae radix on the morphology and viability of mesenchymal stem cells derived from the gingiva. Mesenchymal stem cells derived from the gingiva were grown in the presence of Angelicae dahuricae radix at final concentrations that ranged from 0.001 to 100 µg/ml. The morphology of the cells was viewed under an inverted microscope, and the analysis of cell proliferation was performed with cell counting kit-8 (CCK-8) on days 1, 3 and 7. The cells in the control group had spindle-shaped, fibroblast-like morphology at days 1, 3 and 7 under optical microscopy. The shapes of the cells in 0.001, 0.01, 0.1, 1, 10 and 100 µg/ml Angelicae dahuricae radix were similar to the shapes of the cells in the control group. The relative values of the CCK-8 assays of 0.001, 0.01, 0.1, 1, 10, and 100 µg/ml Angelicae dahuricae radix were 102.5 ± 0.6, 133.3 ± 9.6, 148.4 ± 20.5, 147.7 ± 12.6, 132.3 ± 27.7 and 101.1 ± 4.6%, respectively, when the CCK-8 result of the control group on day 1 was considered to be 100%. There was a marginal increase in cell proliferation at 0.1 and 1 µg/ml groups at day 1; however, this did not achieve statistical significance (P=0.052). The relative values of the CCK-8 assays of 0.001, 0.01, 0.1, 1, 10 and 100 µg/ml Angelicae dahuricae radix were 96.5 ± 1.3, 89.3 ± 0.9, 90.3 ± 3.0, 84.8 ± 12.2, 92.3 ± 4.5 and 86.8 ± 11.7%, respectively, when the CCK-8 result of the control group on day 3 was considered to be 100% (P>0.05). The relative values of the CCK-8 assays of 0.001, 0.01, 0.1, 1, 10 and 100 µg/ml Angelicae dahuricae radix day 7 were 94.9 ± 22.3, 102.8 ± 22.1, 127.4 ± 7.4, 130.4 ± 1.3, 129.2 ± 10.8 and 124.8 ± 9.1%, respectively, when the CCK-8 result of the control group on day 7 was considered to be 100%, but there were no statistically significant differences among the groups (P>0.05). Within the limits of this study, Angelicae dahuricae radix at the tested concentrations did not produce statistically significant differences in the viability of stem cells derived from the gingiva.