Chitosan/Hyaluronan and Alginate-Nanohydroxyapatite Biphasic Scaffold as a Promising Matrix for Osteoarthritis Disorders

Purpose

Regenerative medicine offers new techniques for osteoarthritis (OA) disorders, especially while considering simultaneous chondral and subchondral regenerations.

Methods

Chitosan and hyaluronan were chemically bound as the chondral phase and the osteogenic layer was prepared with alginate and nano-hydroxyapatite (nHAP). These scaffolds were fixed by fibrin glue as a biphasic scaffold and then examined.

Results

Scanning electron microscopy (SEM) confirmed the porosity of 61.45±4.51 and 44.145±2.81 % for the subchondral and chondral layers, respectively. The composition analysis by energy dispersive X-ray (EDAX) indicated the various elements of both hydrogels. Also, their mechanical properties indicated that the highest modulus and resistance values corresponded to the biphasic hydrogel as 108.33±5.56 and 721.135±8.21 kPa, despite the same strain value as other groups. Their individual examinations demonstrated the proteoglycan synthesis of the chondral layer and also, the alkaline phosphatase (ALP) activity of the subchondral layer as 13.3±2.2 ng. After 21 days, the cells showed a mineralized surface and a polygonal phenotype, confirming their commitment to bone and cartilage tissues, respectively. Immunostaining of collagen I and II represented greater extracellular matrix (ECM) secretion in the biphasic composite group due to the paracrine effect of the two cell types on each other.

Conclusion

For the first time, the ability of this biphasic scaffold to regenerate both tissue types was evaluated and the results showed satisfactory cellular commitment to bone and cartilage tissues. Thus, this scaffold can be considered a new strategy for the preparation of implants for OA.

Physical, mechanical, and biological performance of chitosan-based nanocomposite coating deposited on the polycaprolactone-based 3D printed scaffold: Potential application in bone tissue engineering

Recently, coating on composite scaffolds has attracted many researchers' attention to improve scaffolds' properties. In this research, a 3D printed scaffold was fabricated from polycaprolactone (PCL)/magnetic mesoporous bioactive glass (MMBG)/alumina nanowire (Al₂O₃, Optimal percentage 5 %) (PMA) and then coated with chitosan (Cs)/multi-walled carbon nanotubes (MWCNTs) by an immersion coating method. Structural analyses such as XRD and ATR-FTIR confirmed the presence of Cs and MWCNTs in the coated scaffolds. The SEM results of the coated scaffolds showed homogeneous three-dimensional structures with interconnected pores compared to the uncoated scaffolds. The coated scaffolds exhibited an increase in compression strength (up to 16.1 MPa) and compressive modulus (up to 40.83 MPa), improved surface hydrophilicity (up to 32.69°), and decrease in degradation rate (68 % remaining weight) compared to the uncoated scaffolds. The increase in apatite formation in the scaffold coated with Cs/MWCNTs was confirmed by SEM, EDAX, and XRD tests. Coating the PMA scaffold with Cs/MWCNTs leads to the viability and proliferation of MG-63 cells and more secretion of alkaline phosphatase and Ca activity, which can be introduced as a suitable candidate for use in bone tissue engineering.

The role of three-dimensional scaffolds based on polyglycerol sebacate/ polycaprolactone/ gelatin in the presence of Nanohydroxyapatite in promoting chondrogenic differentiation of human adipose-derived mesenchymal stem cells

BACKGROUND

Tissue engineering for cartilage regeneration has made great advances in recent years, although there are still challenges to overcome. This study aimed to evaluate the chondrogenic differentiation of human adipose-derived mesenchymal stem cells (hADSCs) on three-dimensional scaffolds based on polyglycerol sebacate (PGS) / polycaprolactone (PCL) / gelatin(Gel) in the presence of Nanohydroxyapatite (nHA).

MATERIALS AND METHODS

In this study, a series of nHA-nanocomposite scaffolds were fabricated using 100:0:0, 60:40:0, and 60:20:20 weight ratios of PGS to PCL: Gel copolymers through salt leaching method. The morphology and porosity of prepared samples was characterized by SEM and EDX mapping analysis. Also, the dynamic contact angle and PBS adsorption tests are used to identify the effect of copolymerization and nanoparticles on scaffolds' hydrophilicity. The hydrolytic degradation properties were also analyzed. Furthermore, cell viability and proliferation as well as cell adhesion are evaluated to find out the biocompatibility. To determine the potential ability of nHA-nanocomposite scaffolds in chondrogenic differentiation, RT-PCR assay was performed to monitor the expression of collagen II, aggrecan, and Sox9 genes as markers of cartilage differentiation.

RESULTS

The nanocomposites had an elastic modulus within a range of 0.71-1.30 MPa and 0.65-0.43 MPa, in dry and wet states, respectively. The PGS/PCL sample showed a water contact angle of 72.44 ± 2.2°, while the hydrophilicity significantly improved by adding HA nanoparticles. It was found from the hydrolytic degradation study that HA incorporation can accelerate the degradation rate compared with PGS and PGS/PCL samples. Furthermore, the in vitro biocompatibility tests showed significant cell attachment, proliferation, and viability of adipose-derived mesenchymal stem cells (ADMSCs). RT-PCR also indicated a significant increase in collagen II, aggrecan and Sox9 mRNA levels.

CONCLUSIONS

Our findings demonstrated that these nanocomposite scaffolds promote the differentiation of hADSCs into chondrocytes possibly by the increase in mRNA levels of collagen II, aggrecan, and Sox9 as markers of chondrogenic differentiation. In conclusion, the addition of PCL, Gelatin, and HA into PGS is a practical approach to adjust the general features of PGS to prepare a promising scaffold for cartilage tissue engineering.

Biomimetic biphasic scaffolds in osteochondral tissue engineering: Their composition, structure and consequences

Approaches to the design and construction of biomimetic scaffolds for osteochondral tissue, show increasing advances. Considering the limitations of this tissue in terms of repair and regeneration, there is a need to develop appropriately designed scaffolds. A combination of biodegradable polymers especially natural polymers and bioactive ceramics, shows promise in this field. Due to the complicated architecture of this tissue, biphasic and multiphasic scaffolds containing two or more different layers, could mimic the physiology and function of this tissue with a higher degree of similarity. The purpose of this review article is to discuss the approaches focused on the application of biphasic scaffolds for osteochondral tissue engineering, common methods of combining layers and the ultimate consequences of their use in patients were discussed.

Elderberry diet improves gut-brain axis dysfunction, neuroinflammation, and cognitive impairment in the rat model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is related to a problem in the gut-brain axis. This experimental research aimed to shed light on the potential therapeutic application of elderberry (EB), which can work on the axis and get better the IBS symptoms. There were three groups (36 Sprague-Dawley rats) in this experiment, including control, IBS, and IBS with EB diet (IBS + EB). Making use of intracolonic instillation of 1 ml of 4% acetic acid for 30 s, IBS was induced. 7 days later, the EB extract (2%) was added to the diets of all animals for 8 weeks. Some histological, behavioral, and stereological techniques were used to detect the effects of EB on the gut and brain tissues. The findings showed that the EB diet improved locomotion and decreased anxiety-like behavior in the rat models of IBS. Moreover, the diet dropped the expression of TNF-α and increased mucosal layer thickness and the number of goblet and mast cells in colon tissue samples. In the hippocampal samples, administration of EB prevented astrogliosis and astrocyte reactivity. Although hippocampal and cortical neurons decreased markedly in the IBS group, EB prevented the drop in the number of neurons. Although lots of research is needed to elucidate the effectiveness of EB in IBS and its exact molecular mechanism, the result of this study showed that EB as an antioxidant and immune-modulatory agent could be a promising research target to prevent the impairment in the gut-brain axis, and could ameliorative classic IBS symptoms.

Polyhydroxybutyrate-starch/carbon nanotube electrospun nanocomposite: A highly potential scaffold for bone tissue engineering applications

Blend nanofibers composed of synthetic and natural polymers with carbon nanomaterial, have a great potential for bone tissue engineering. In this study, the electrospun nanocomposite scaffolds based on polyhydroxybutyrate(PHB)-Starch-multiwalled carbon nanotubes (MWCNTs) were fabricated with different concentrations of MWCNTs including 0.5, 0.75 and 1 wt%. The synthesized scaffolds were characterized in terms of morphology, porosity, thermal and mechanical properties, biodegradation, bioactivity, and cell behavior. The effect of the developed structures on MG63 cells was determined by real-time PCR quantification of collagen type I, osteocalcin, osteopontin and osteonectin genes. Our results showed that the scaffold containing 1 wt% MWCNTs presented the lowest fiber diameter (124 ± 44 nm) with a porosity percentage above 80 % and the highest tensile strength (24.37 ± 0.22 MPa). The addition of MWCNTs has a positive effect on surface roughness and hydrophilicity. The formation of calcium phosphate sediments on the surface of the scaffolds after immersion in SBF is observed by SEM and verified by EDS and XRD analysis.MG63 cells were well cultured on the scaffold containing MWCNTs and presented more cell viability, ALP secretion, calcium deposition and gene expression compared to the scaffolds without MWCNTs. The PHB-starch-1wt.%MWCNTs scaffold can be considerable for studies of supplemental bone tissue engineering applications.

Anti-inflammatory effect of green photobiomodulation in human adipose-derived mesenchymal stem cells

Photo biomodulation (PBM) as a non-invasive and safe treatment has been demonstrated the anti-inflammatory potential in a variety of cell types, including stem cells. However, further investigations using different laser parameters combined with more accurate methods such as quantitative measurement of inflammatory gene expression at the mRNA level are still necessary. The aim of this study was to evaluate the effect of 532 nm green laser on cell proliferation as well as expression of inflammatory genes in human adipose-derived mesenchymal stem cells (hADMSCs) using RNA sequencing (RNA-seq) technique and confirmatory RT-PCR. hADMSCs were cultured in DMEM low glocuse medium with 10% fetal bovine serum until the fourth passage. Cultured cells were divided in two groups: control group (no laser irradiation) and laser group, irradiated with 532 nm laser at 44 m J/cm² with an output power of 50 mW and a density of 6 mW/cm², every other day, 7 s each time. The cell viability was assessed using MTT assay 24 h after each irradiation on days 3, 5, and 7 after cell seeding, followed by performing RNA-seq and RT-PCR. The MTT assay showed that PBM increased cell proliferation on day 5 after irradiation compared to day 3 and decreased on day 7 compared to day 5. In addition, gene expression analysis in hADMSCs using RNA-seq revealed down-regulation of inflammatory genes including CSF2, CXCL2, 3, 5, 6, 8, and CCL2, 7. These results indicate that 532 nm PBM with the parameters used in this study has a time-dependent effect on hADMSCs proliferation as well as anti-inflammatory potential.

Evaluation of the effects of starch on polyhydroxybutyrate electrospun scaffolds for bone tissue engineering applications

Efficient design for bone tissue engineering requires an understanding of the appropriate selection of biomimetic natural or synthetic materials and scalable fabrication technologies. In this research, poly (3-hydroxybutyrate) (PHB) and starch (5-15 wt%) as biological macromolecules were used to fabricate novel biomimetic scaffolds by electrospinning method. SEM results of electrospun scaffolds revealed bead-free nanofibers and three-dimensional homogenous structures with highly interconnected pores. Results of FTIR and Raman demonstrated that there were hydrogen bonds between the two polymers. The tensile strength of scaffolds was significantly improved by adding starch up to 10 wt%, from 3.05 to 15.54 MPa. In vitro degradation and hydrophilicity of the scaffolds were improved with the presence of starch. The viability and proliferation of MG-63 cells and alkaline phosphatase (ALP) activity were remarkably increased in the PHB-starch scaffolds compared to the PHB and control samples. The mineralization and calcium deposition of MG-63 cells were confirmed by alizarin red staining. It is concluded that PHB/starch electrospun scaffold could be a good candidate for bone tissue engineering applications.

Inflammatory Response Leads to Neuronal Death in Human Post-Mortem Cerebral Cortex in Patients with COVID-19

The recent coronavirus disease of 2019 (COVID-19) pandemic has adversely affected people worldwide. A growing body of literature suggests the neurological complications and manifestations in response to COVID-19 infection. Herein, we explored the inflammatory and immune responses in the post-mortem cerebral cortex of patients with severe COVID-19. The participants comprised three patients diagnosed with severe COVID-19 from March 26, 2020, to April 17, 2020, and three control patients. Our findings demonstrated a surge in the number of reactive astrocytes and activated microglia, as well as low levels of glutathione along with the upregulation of inflammation- and immune-related genes IL1B, IL6, IFITM, MX1, and OAS2 in the COVID-19 group. Overall, the data imply that oxidative stress may invoke a glial-mediated neuroinflammation, which ultimately leads to neuronal cell death in the cerebral cortex of COVID-19 patients.

Pulp ECM-derived macroporous scaffolds for stimulation of dental-pulp regeneration process

OBJECTIVE

Recent studies suggest xenogeneic extracellular matrices as potential regenerative tools in dental pulp regeneration. This study aimed to fabricate and characterize a novel three-dimensional macroporous pulp-derived scaffold that enables the attachment, penetration, proliferation and differentiation of mesenchymal stem cells.

METHOD

Bovine pulp was decellularized and characterized with histological and DNA content methods. This scaffold was prepared using finely milled lyophilized decellularized pulp extracellular matrix (ECM) digested with pepsin. Three different concentrations of ECM (1.50, 2.25 and 3.00mg/ml) were freeze-dried and were tested with/without chemical crosslinking. The specimens were subjected to physicochemical characterization, cell viability and quantitative real time polymerase chain reaction assessments with human bone marrow mesenchymal stem cells (hBMMSCs). All scaffolds were subcutaneously implanted in rats for two weeks and histological and immunostaining analyses were performed.

RESULTS

Histological and DNA analysis confirmed complete decellularization. All samples demonstrated more than 97% porosity and 1.50mg/ml scaffold demonstrated highest water absorption. The highest cell viability and proliferation of hBMMSCs was observed on the 3.00mg/ml crosslinked scaffolds. The gene expression analysis showed a significant increase of dmp-1 and collagen-I on 3.00mg/ml crosslinked scaffolds compared to the other scaffolds. Histological examination of subcutaneous implanted scaffolds revealed low immunological response, and enhanced angiogenesis in cross-linked samples compared to non-crosslinked samples.

SIGNIFICANCE

The three-dimensional macroporous pulp-derived injectable scaffold developed and characterized in this study displayed potential for regenerative therapy. While the scaffold biodegradability was decreased by crosslinking, the biocompatibility of post-crosslinked scaffold was significantly improved.