Comparative study of poly(L-lactic acid) scaffolds coated with chitosan nanoparticles prepared via ultrasonication and ionic gelation techniques

Poly-ε-caprolactone (PCL)/poly-l-lactic acid (PLLA) nanofibers loaded by nanoparticles-containing TGF-β1 with linearly arranged transforming structure as a scaffold in cartilage tissue engineering

This study aimed to present a novel three-dimensional nanocomposite scaffold using poly-ε-caprolactone (PCL), containing transforming growth factor-beta 1 (TGF-β1)-loaded chitosan-dextran nanoparticles and poly-l-lactic acid (PLLA), to make use of nanofibers and nanoparticles simultaneously. The electrospinning method fabricated a bead-free semi-aligned nanofiber composed of PLLA, PCL, and chitosan-dextran nanoparticles containing TGF-β1. A biomimetic scaffold was constructed with the desired mechanical properties, high hydrophilicity, and high porosity. Transmission electron microscopy findings showed a linear arrangement of nanoparticles along the core of fibers. Based on the results, burst release was not observed. The maximum release was achieved within 4 days, and sustained release was up to 21 days. The qRT-PCR results indicated an increase in the expression of aggrecan and collagen type Ι genes compared to the tissue culture polystyrene group. The results indicated the importance of topography and the sustained release of TGF-β1 from bifunctional scaffolds in directing the stem cell fate in cartilage tissue engineering.

Sustained release of valproic acid loaded on chitosan nanoparticles within hybrid of alginate/chitosan hydrogel with/without stem cells in regeneration of spinal cord injury

Hydrogels have been increasingly applied in tissue regeneration and drug delivery systems (DDS). In this study, the capacity of valproic acid (Val) encapsulated within hybrid of alginate (Alg)-chitosan (Cs) (Alg-Cs) hydrogel containing Cs nanoparticle (Npch) with/without human endometrial stem cells (hEnSC) was initially examined for regeneration of spinal cord injury (SCI). To evaluate the stability of the synthesized hydrogels zeta potential necessary measurements were made. Physicochemically, the developed hydrogels were evaluated using Fourier-transform infrared (FTIR) spectroscopy. The physical properties including degradation rate, swelling ability, and tunability of the synthesized hydrogels were studied. To evaluate the nerve regeneration ability of the synthesized hydrogels, 35 Sprague-Dawley rats were undergone SCI. The spinal cords were exposed using laminectomy in T9-T10 area and the hemi-section SCI model was made. The rats were then randomly divided into 5 groups (n = 7) including, Alg-Cs/Npch, Alg-Cs/Npch/hEnSCs, Alg-Cs/Npch/Val, and Alg-Cs/Npch/hEnScs/Val, and the control groups without any intervention. The FTIR spectra showed band frequencies and assignments of Val, Alg-Cs, and alginate. Nanoparticles were formulated with a mean diameter of 187 and 210 nm, for Val/Alg-Cs and Alg-Cs, respectively. The loading of Val into Alg-Cs led to its reduced size by about 40 nm. The Cs-Npch/Val hydrogels degraded faster than the Alg-Cs-/Npch/Val hydrogel specifically in extended time of incubation. A higher swelling capacity of Alg-Cs/Npch hydrogel, compared to Cs/Npch/Val and Alg-Cs/Npch/Val hydrogels, was found. The Cs-Npch/Val hydrogels degraded faster than Alg-Cs-/Npch/Val hydrogel. The Alg-Cs/Npch/hEnSCs/Val could regenerate the damaged nerve fibers and histologically prevent the SCI-induced vacuolization spaces. The prepared Alg-Cs/Npch/Val could be a suitable polymeric carrier for taurine drugs as bioactive substrate in nerve tissue engineering (NTE) and DDS.

PCL NGCs integrated with urolithin-A-loaded hydrogels for nerve regeneration

Inflammation and oxidative stress are among the leading causes of poor prognosis after peripheral nerve injury (PNI). Urolithin-A (UA), an intermediate product produced by the catabolism of ellagitannins in the gastrointestinal tract, has anti-inflammatory, antioxidant, and immunomodulatory properties for inflammation, oxidative damage, and aging-related diseases. Hence, we prepared UA-loaded hydrogels and embedded them in the lumen of PCL nerve guide conduits (NGCs). The hydrogels continuously released appropriate doses of UA into the microenvironment. Based on in vitro studies, UA facilitates cell proliferation and reduces oxidative damage. Besides, the experimental evaluation revealed good biocompatibility of the materials involved. We implanted NGCs into rat models to bridge the sciatic nerve defects in an in vivo study. The sciatic functional index of the PCL/collagen/UA group was comparable to that of the autograft group. Additionally, the consequences of electrophysiological, gastrocnemius muscle and nerve histology assessment of the PCL/collagen/UA group were better than those in the PCL and PCL/collagen groups and close to those in the autograft group. In this study, UA sustained release via the PCL/collagen/UA NGC was found to be an effective alternative treatment for PNI, validating our hypothesis that UA could promote regeneration of nerve tissue.

Advanced Hydrogels for Cartilage Tissue Engineering: Recent Progress and Future Directions

Cartilage is a tension- and load-bearing tissue and has a limited capacity for intrinsic self-healing. While microfracture and arthroplasty are the conventional methods for cartilage repair, these methods are unable to completely heal the damaged tissue. The need to overcome the restrictions of these therapies for cartilage regeneration has expanded the field of cartilage tissue engineering (CTE), in which novel engineering and biological approaches are introduced to accelerate the development of new biomimetic cartilage to replace the injured tissue. Until now, a wide range of hydrogels and cell sources have been employed for CTE to either recapitulate microenvironmental cues during a new tissue growth or to compel the recovery of cartilaginous structures via manipulating biochemical and biomechanical properties of the original tissue. Towards modifying current cartilage treatments, advanced hydrogels have been designed and synthesized in recent years to improve network crosslinking and self-recovery of implanted scaffolds after damage in vivo. This review focused on the recent advances in CTE, especially self-healing hydrogels. The article firstly presents the cartilage tissue, its defects, and treatments. Subsequently, introduces CTE and summarizes the polymeric hydrogels and their advances. Furthermore, characterizations, the advantages, and disadvantages of advanced hydrogels such as multi-materials, IPNs, nanomaterials, and supramolecular are discussed. Afterward, the self-healing hydrogels in CTE, mechanisms, and the physical and chemical methods for the synthesis of such hydrogels for improving the reformation of CTE are introduced. The article then briefly describes the fabrication methods in CTE. Finally, this review presents a conclusion of prevalent challenges and future outlooks for self-healing hydrogels in CTE applications.

Effectiveness of Green Synthesis of Silver/Kaolinite Nanocomposite Using Quercus infectoria Galls Aqueous Extract and Its Chitosan-Capped Derivative on the Healing of Infected Wound

Kaolinite nanocomposites (NCs) could be utilized as agents for wound healing owing to their efficiency and low toxicity. The present study was conducted to synthesize a novel silver/kaolinite NCs (Ag/Kaol NCs) and investigate their chitosan derivation (Ag/Kaol/Chit NCs) using oak extract. XRD, SEM, EDX, FT-IR, and DLS were employed for the investigation of structural and physio-chemical properties of the synthesized NCs. The obtained results revealed that synthesized Ag/Kaol NCs were mesoporous and spherical with sizes ranging from 7-11 nm. They also demonstrated successful synthesis between silver and kaolinite using the extract. Cytotoxicity and in vitro antibacterial activity were also investigated. The clinical effects of ointments containing the NCs for improving wound healing were studied on the wound area, total bacterial count, histological parameters, and protein expression of some genes. Nanocomposites were safe up to 0.50 mg/mL. The results of in vivo and in vitro antibacterial activity showed that Ag/Kaol NCs, were of antibacterial activity ( ). The results of antioxidant activity indicated that Ag/Kaol NCs have antioxidant structures. Our findings concerning molecular mechanism implied that Ag/Kaol/Chit increased the expression of Wnt/ β -catenin and collagen ( ). In sum, Ag/Kaol/Chit showed antibacterial activity and improved wound healing by decreasing the inflammation and promoting the proliferative phase. The novel NCs showed wound healing properties by decreasing inflammation and total bacterial count and increasing proliferative phase. The application of Ag/Kaol/Chit was suggested as a green agent for improving infected wound healing.

Kaolin-loaded chitosan/polyvinyl alcohol electrospun scaffold as a wound dressing material: in vitro and in vivo studies

OBJECTIVE

To evaluate the application of a fabricated dressing containing kaolin for skin regeneration in a rat model of excisional wounds.

METHOD

In the present study, kaolin was loaded into electrospun polyvinyl alcohol (PVA)/chitosan polymer blend to develop a composite nanofibrous dressing. To make the yarns, kaolin with weight ratio of 5% was added to PVA/chitosan polymer blend and subsequently formed into nanofibres using the electrospinning method. Scaffolds were evaluated for to their microstructure, mechanical properties, surface wettability, water vapour transmission rate, water-uptake capacity, blood uptake capacity, blood compatibility, microbial penetration test, the number of colonies, and cellular response with the L929 cell line. Rats with full-thickness excisional wounds were treated with kaolin-containing and kaolin-free dressings.

RESULTS

The study showed that rats treated with the kaolin-incorporated mats demonstrated a significant closure to nearly 97.62±4.81% after 14 days compared with PVA/chitosan and the sterile gauze, which showed 86.15±8.11% and 78.50±4.22% of wound closure, respectively. The histopathological studies showed that in the PVA/chitosan/kaolin group, dense and regular collagen fibres were formed, while wounds treated with sterile gauze or PVA/chitosan scaffolds had random and loose collagen fibres.

CONCLUSION

Our results show the potential applicability of PVA/chitosan/kaolin scaffolds as a wound care material.

Sciatic nerve regeneration by using collagen type I hydrogel containing naringin

In the present study, collagen hydrogel containing naringin was fabricated, characterized and used as the scaffold for peripheral nerve damage treatment. The collagen was dissolved in acetic acid, naringin added to the collagen solution, and cross-linked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide powder (EDC; 0.10 mM) to form the hydrogel. The microstructure, swelling behavior, biodegradation, and cyto/hemocompatibility of the fabricated hydrogels were assessed. Finally, the healing efficacy of the prepared collagen hydrogel loaded with naringin on the sciatic nerve crush injury was assessed in the animal model. The characterization results showed that the fabricated hydrogels have a porous structure containing interconnected pores with the average pore size of 90 µm. The degradation results demonstrated that about 70% of the primary weight of the naringin loaded hydrogel had been lost after 4 weeks of storage in PBS. The in vitro study showed that the proliferation of Schwann cells on the collagen/naringin hydrogel was higher than the control group (tissue culture plate) at both 48 and 72 h after cell seeding and even significantly higher than pure collagen 72 h after cell seeding (*p < 0.005, **p < 0.001). The animal study implied that the sciatic functional index reached to -22.13 ± 3.00 at the end of 60th days post-implantation which was statistically significant (p < 0.05) compared with the negative control (injury without the treatment) (-82.60 ± 1.06), and the pure collagen hydrogel (-59.80 ± 3.20) groups. The hot plate latency test, the compound muscle action potential, and wet weight-loss of the gastrocnemius muscle evaluation confirmed the positive effect of the prepared hydrogels on the healing process of the induced nerve injury. In the final, the histopathologic examinations depicted that the collagen/naringin hydrogel group reduced all the histological changes induced from the nerve injury and showed more resemblance to the normal sciatic nerve, with well-arranged fibers and intact myelin sheath. The overall results implied that the prepared collagen/naringin hydrogel can be utilized as a sophisticated alternative to healing peripheral nerve damages.

Engineering of extracellular vesicles as drug delivery vehicles

Extracellular vesicles (EVs) are secreted membrane-enclosed nano-sized particles (40-1,000 nm) that deliver biological information between cells. The molecular composition of these subcellular particles includes growth factor receptors, ligands adhesion proteins, mRNA, miRNAs, lncRNA and lipids that are derived from donor cells. A number of studies demonstrated that stem cell-derived EVs are the key mediator of tissue repair and regeneration in multiple animal disease models. In addition, the composition of these particles is known to be altered in cancer and disease pathology suggesting them for useful in diagnostic and therapeutic purposes. Their endogenous origin and biological properties offer benefits over conventional drug delivery systems (DDS), such as liposome, synthetic nanoparticles and prompted the further application of EVs as drug delivery vehicles for chemical drugs, genetic materials and proteins. The contents of EVs can be efficiently modified by chemical, biological or physical means. Thus, EVs can be an innovative DDS as it can overcome physical and biological barriers and safely deliver therapeutic drugs to target tissues. In this minireview, we summarized current progress on the strategies of drug loading onto EVs; ex vivo and in vivo loading.

Bio-based materials with novel characteristics for tissue engineering applications - A review

Recently, a wider spectrum of bio-based materials and materials-based novel constructs and systems has been engineered with high interests. The key objective is to help for an enhanced/better quality of life in a secure way by avoiding/limiting various adverse effects of some in practice traditional therapies. In this context, different methodological approaches including in vitro, in vivo, and ex vivo techniques have been exploited, so far. Among them, bio-based therapeutic constructs are of supreme interests for an enhanced and efficient delivery in the current biomedical sector of the modern world. The development of new types of novel, effective and highly reliable materials-based novel constructs for multipurpose applications is essential and a core demand to tackle many human health related diseases. Bio-based materials possess several complementary functionalities, e.g. unique chemical structure, bioactivity, non-toxicity, biocompatibility, biodegradability, recyclability, etc. that position them well in the modern world's materials sector. In this context, the utilization of biomaterials provides extensive opportunities for experimentation in the field of interdisciplinary and multidisciplinary scientific research. With an aim to address the global dependence on petroleum-based polymers, researchers have been redirecting their interests to the engineering of biological materials for targeted applications in different industries including cosmetics, pharmaceuticals, and other biotechnological or biomedical applications. Herein, we reviewed biotechnological advancements at large and tissue engineering from a biomaterials perspective in particular and envision directions of future developments.