Arian Ehterami

Peripheral nerve injuries are a major clinical challenge, interrupting neural connectivity between the central nervous system (CNS) and peripheral organs. Traumatic events, natural disasters, and accidents often cause these complex injuries. Recent studies highlight the neurogenic potential of dexamethasone, retinoic acid, and umbilical cord blood stem cells in promoting nerve regeneration. Therefore, the aim of this study was to design electrospun conduits based on PLCL, gelatin, and collagen, along with dexamethasone, retinoic acid, carboxymethyl chitosan, and umbilical cord blood cells to repair sciatic nerve injuries. The chemical and physical properties of the conduits, in addition to biocompatibility and cytotoxicity, were evaluated with different experiments. Finally, the conduits were implanted into a 10 mm defect in the mouse sciatic nerve, and tissue regeneration was assessed after 3 months by related tests. The results showed that the presence of dexamethasone in the conduit designed improved biocompatibility, wettability, degradation rate, tensile strength, and increased cell viability. After seeding the umbilical cord blood cells on the conduit, the results showed good efficacy of the conduit, improving sensory and motor function and increasing nerve regeneration. These results indicate the potential of the resulting conduits as a promising tool for repairing nerve injuries and clinical trials.

Over the past two decades, stents have revolutionized the treatment of cardiovascular diseases, particularly coronary artery and valvular heart disease. In this Review, we evaluate the clinical challenges associated with these diseases, as well as the manufacturing strategies for both coronary and heart valve stents, with a focus on the emerging role of 3D printing. Specifically, we assess the advantages and limitations of clinically available metallic and polymeric stents for coronary artery disease and provide an overview of the metallic and biodegradable polymeric stents developed to treat valvular heart disease. Furthermore, we explore the capabilities of key 3D-printing methods for stent fabrication, highlighting their strengths and drawbacks, and discuss the regulatory considerations that govern the clinical translation of 3D printing-based coronary and valvular stents. Taken together, 3D-printing technologies offer new opportunities to customize geometry, control stent degradation and improve stent implantation approaches for patients with complex anatomies. By merging innovations in material science, manufacturing strategies and bioengineering, 3D-printing technology has a major role in the next generation of personalized and multifunctional cardiovascular stents.

Background: The extracellular matrix (ECM) plays a central role in the mechanical strength and functional integration of tissue-engineered matrix (TEM), particularly in cardiovascular and load-bearing applications. Mesenchymal stromal cells (MSCs) from different sources may vary in their ECM-forming potential. Methods: In this study, adipose-derived (hADMSC), bone marrow-derived (hBMSC), and umbilical cord-derived MSCs (hUCMSC) were compared with human dermal fibroblasts (HDFBs) as a reference. Cells were seeded onto polyglycolic acid (PGA)/poly-4-hydroxybutyrate (P4HB) scaffolds and cultured for 3 weeks under static or hydrodynamic conditions using orbital shaking. TEM development was assessed macroscopically, histologically (using H&E and Masson’s trichrome stains), and by polarized light microscopy (Picrosirius Red), alongside biochemical assays that quantified DNA, glycosaminoglycan (GAGs), and hydroxyproline (HYP). Results: Hydrodynamically stimulated culture consistently improved ECM deposition across all groups. TEMs exposed to hydrodynamic stimulation (hydrodynamic conditions) were thicker, more uniformly filled, and exhibited increased collagen deposition compared with static TEMs, which remained thinner and showed persistent scaffold remnants. Polarized light analysis demonstrated that dynamic loading promoted collagen maturation in all groups, as evidenced by an increased prevalence of thick, birefringent collagen fibers indicative of mature collagen. Biochemical analyses showed that HDFB-derived TEMs produced the highest total collagen and ECM content under both static and hydrodynamic conditions; however, these matrices remained comparatively thin and densely packed. In contrast, MSC-derived TEMs formed thicker and more spatially distributed ECM in response to hydrodynamic stimulation. Conclusion: Among the MSC sources, hUCDMSC-derived TEMs exhibited the most advanced collagen maturation and the most uniform collagen distribution under hydrodynamically stimulated culture, whereas hADMSC-derived TEMs showed the greatest matrix thickening and volumetric ECM expansion with intermediate collagen maturation. hBMSC-derived TEMs displayed clear responsiveness to hydrodynamic stimulation but remained limited in overall collagen deposition and fiber maturation. These findings underscore that both hydrodynamic stimulation and cell source are critical not only for maximizing ECM deposition, but also for ensuring physiologically relevant collagen maturation and matrix organization in grafts suitable for clinical translation.

Regenerative medicine aims to restore damaged tissues or organs using stem cells, biomaterials, and decellularized grafts. Peripheral nerve injuries (PNI), affecting 2.8% of patients, lead to severe functional impairments with global socioeconomic costs exceeding $7 billion annually. Despite advancements in surgical techniques, full functional recovery remains elusive, particularly in critical gap injuries (> 3 cm). Autografts remain the gold standard but are hindered by donor tissue scarcity and complications like neuroma formation. Allografts face challenges due to the lack of Schwann cells and neurotrophic support. Emerging approaches in tissue engineering leverage synthetic materials, such as polycaprolactone (PCL) and polylactic acid (PLA), and biological scaffolds like decellularized nerve grafts. These innovations provide structural support, promote axonal regeneration, and retain extracellular matrix components, enabling cell adhesion and migration while minimizing antigenicity. However, barriers such as mechanical instability, scar tissue formation, and inadequate cellularization persist. This review explores the anatomy and clinical significance of the sciatic nerve, historical perspectives on peripheral nerve repair, and current treatment strategies. It evaluates biological and synthetic nerve conduits, highlighting FDA‐approved products and their advantages in promoting nerve regeneration. Additionally, the paper discusses challenges in the field, including limited functional recovery and the need for more effective clinical solutions. By combining natural and synthetic materials with growth factor delivery and vascularization strategies, engineered scaffolds hold promise for improving outcomes in PNI repair. Further research is essential to optimize these technologies and bridge existing gaps in clinical practice.

A functional and biocompatible biomaterial is essential for accelerating the regeneration of skin tissue at the wound site. Hydrogel scaffolds in three dimensions show promising candidates for this purpose. This study was conducted to design a novel porous cross-linked alginate (Alg) hydrogel containing green tea (GT) and assess its morphology, swelling, weight loss, hemocompatibility, and cytocompatibility. Ultimately, the created hydrogel’s therapeutic effectiveness was examined in a complete dermal diabetes wound model. The findings indicated that the hydrogel prepared had significant porosity, with interconnected pores around 75.821 µm in size. The weight loss evaluation indicated that the created hydrogel can be degraded naturally, with a weight loss ratio of about 74% for Alg/GT 80 mg after being incubated for 24 hours. Additionally, the study indicated that hydrogel dressings exhibited greater wound closure compared to gauze-treated wounds, which served as the control. The group with GT at a concentration of 80 mg showed the highest percentage of wound closure. The histopathological studies and IHC evaluation for TGF-β1 confirmed the in vivo finding. This study proposes utilizing 3D Alg hydrogels with GT as a wound dressing, but further studies are needed.

This study focuses on the development of a 3-dimensional porous scaffold using Polycaprolactone/Gelatin/Nanoclay (PCL/GNF/NC) for bone tissue engineering. The scaffold incorporates varying dosages of silybin (Sil) through a mixture of electrospinning and thermal-induced phase separation (TIPS) techniques. Assessments of surface shape, porosity, compressive strength, water contact angle, degradation rate, releasing profile, hemolysis, and cell proliferation were among the investigations carried out to appraise the manufactured scaffolds. In vivo evaluation utilized a rat calvaria defect model, with histological analysis employed to assess the results. The scaffolds exhibited porosity within the range of 70-90%, and those containing silybin demonstrated lower compressive strength and contact angle, along with a higher degradation rate compared to those without silybin. Release experiments revealed a 61.09% release of silybin after 28 days. In both in vivo and in vitro assessments, the PCL/GNF/NC/Sil1% scaffold displayed superior cell proliferation and bone healing properties compared to other groups. These findings suggest the potential efficacy of silybin in bone defect treatment, warranting further investigation in future research.

Skin tissue engineering has gained significant attention as a promising alternative to traditional treatments for skin injuries. In this study, we developed 3D hydrogel-based scaffolds, Alginate, incorporating different concentrations of Curcumin and evaluated their properties, including morphology, swelling behavior, weight loss, as well as hemo- and cytocompatibility. Furthermore, we investigated the therapeutic potential of Alginate hydrogel containing different amounts of Curcumin using an in vitro wound healing model. The prepared hydrogels exhibited remarkable characteristics, SEM showed that the pore size of hydrogels was 134.64 μm with interconnected pores, making it conducive for cellular infiltration and nutrient exchange. Moreover, hydrogels demonstrated excellent biodegradability, losing 63.5% of its weight over 14 days. In addition, the prepared hydrogels had a stable release of curcumin for 3 days. The results also show the hemocompatibility of prepared hydrogels and a low amount of blood clotting. To assess the efficacy of the developed hydrogels, 3T3 fibroblast growth was examined during various incubation times. The results indicated that the inclusion of Curcumin at a concentration of 0.1 mg/mL positively influenced cellular behavior. The animal study showed that Alginate hydrogel containing 0.1 mg/mL curcumin had high wound closure(more than 80%) after 14 days. In addition, it showed up-regulation of essential wound healing genes, including TGFβ1 and VEGF, promoting tissue repair and angiogenesis. Furthermore, the treated group exhibited down-regulation of MMP9 gene expression, indicating a reduction in matrix degradation and inflammation. The observed cellular responses and gene expression changes substantiate the therapeutic efficacy of prepared hydrogels. Consequently, our study showed the healing effect of alginate-based hydrogel containing Curcumin on skin injuries.

Skin damages are usual physical injuries and different studies have been done to improve wound healing. Hydrogel due to its properties like a moist environment and cooling wound site is a good option for wound treatment. In this study, we evaluated the consequence of using alginate/chitosan hydrogel contained various dosages of 4-Methylcatechol (0, 0.1, 1% (W/W)) on wound healing. After hydrogel fabrication, different tests like SEM, swelling, release, weight loss, and hemo- and cytocompatibility were done to characterize fabricated hydrogels. Finally, the rat model was used to assess Alginate/Chitosan hydrogel's therapeutic function containing 0.1 and 1% of 4-Methylcatechol. The pore size of hydrogel was between 24.5 ± 9 and 62.1 ± 11.63 µm and about 90% of hydrogel was lost after 14 days in the weight loss test. Blood compatibility and MTT assay showed that hydrogels were nontoxic and improved cell proliferation. In vivo test showed that Alginate/Chitosan/0.1%4-Methylcatechol improved wound healing and the results were significantly better than the gauze-treated wound. Our results showed dose depending effect of 4-Methylcatechol on wound healing. This study shows the treatment effect of 4-Methylcatechol on wound healing and the possibility of using it for treating skin injuries.