Electrospinning-netting of spider-inspired polycaprolactone/collagen nanofiber-nets incorporated with Propolis extract for enhanced wound healing applications

Nanofibers hold significant promise for wound healing applications, but their potential is limited by their large diameter. To overcome this limitation, the development of nanofibrous systems with refined nanonets (approximately 20 nm in diameter) represents a notable improvement. In this study, a composite of polycaprolactone/collagen (PCLC) nano-fiber/nets (NFNs) was fabricated using benign solvents (acetic acid and formic acid) via the electro-spinning/netting (ESN) technique, harnessing the regenerative potential of collagen as a biological macromolecule. Additionally, to enhance the natural attributes of the NFNs structure, Propolis extract, renowned for its wound healing properties, was incorporated. Five ESN solutions were prepared: PCL, PCLC, PCLC/Pro 5 %, PCLC/Pro 10 %, and PCLC/Pro 15 %. NaCl salt was introduced into all ESN solutions to improve nanonets formation. FE-SEM imaging demonstrated successful nano-net formation in all ESN solutions except for the PCL formulation. The fabricated scaffolds exhibited spider-like nanonets with the addition of collagen and further enhanced nano-net formation with Propolis incorporation. Trunk nanofibers showed filamentous structures without any beads, with an average diameter of 164-728 nm, while the diameter of branched fibers (nanonets) was approximately 20 nm. WVTR values of the NFNs were comparable to commercial dressings such as Tegaderm. The results also demonstrated the potent cytoprotective effects of Propolis-loaded NFNs in a dose-dependent manner. Furthermore, the viability of HFF-2 cells after 72 h of culture on PCLC NFNs significantly increased compared to PCL nanofibers. The highest cell viability was observed in PCLC/Pro 15 % nanofibers after 24, 48, and 72 h of cell culture, indicating the proliferative effect of Propolis extract in nanoformulated form. Additionally, the scaffolds exhibited a hemocompatibility of <3 %, further highlighting their potential in wound healing therapeutics.

Mitochondria-loaded alginate-based hydrogel accelerated angiogenesis in a rat model of acute myocardial infarction

Here, mitochondria were isolated from mesenchymal stem cells (MSCs) after being treated with mitochondria-stimulating substrates, 50 μM metformin (Met), and 40 μM dichloroacetic acid (DCA). The isolated mitochondria (2 × 107 particles) were characterized and encapsulated inside 100 μl hydrogel composed of alginate (3 % w/v; Alg)/gelatin (Gel; 1 % w/v) enriched with 1 μM pyrrole (Pyr) solidified in the presence of 0.2 M FeCl3. The physicochemical properties and cytocompatibility of prepared hydrogels were assessed using FTIR, swelling, biodegradation, porosity assays, and scanning electron microscopy (SEM). The mitochondria-bearing hydrogel was injected into the ischemic area of rat hearts. FTIR absorption bands represented that the addition of FeCl3 led to polypyrrole (PPy) formation, polysaccharide oxidation, and interaction between Alg and Gel. SEM images exhibited porous structure and the size of pores was reduced in Alg/Gel + PPy group compared to Alg + PPy hydrogel. Based on the data, both Alg + PPy and Alg/Gel + PPy hydrogels can preserve the integrity and morphology of loaded mitochondria. It was noted that Alg/Gel + PPy hydrogel possessed a higher swelling ratio, degradation, and porosity compared to Alg + PPy group. Data confirmed that Alg/Gel + PPy hydrogel containing 1 μM Pyr yielded the highest survival rate compared to groups with 2 and 4 μM Pyr (p < 0.05). Injection of mitochondria-loaded Alg/Gel + PPy hydrogel yielded significant restoration of left ventricle thickness compared to the infarction, mitochondria, and Alg/Gel + PPy hydrogel groups 14 days post-injection (p < 0.05). Histological analyses revealed a significant increase of vWF+ capillaries and α-SMA+ arterioles in the mitochondria-loaded Alg/Gel + PPy hydrogel group (p < 0.05). Immunofluorescence imaging revealed the ability of rat cardiomyocytes to uptake mitochondria alone or after being loaded into Alg/Gel + PPy hydrogel. These effects were evident in the Alg/Gel + PPy group. Taken together, electroconductive Alg-based hydrogels are suitable platforms for the transplantation of cells and organelles and the regeneration of ischemic heart changes.

Phenolated alginate hydrogel induced osteogenic properties of mesenchymal stem cells via Wnt signaling pathway

Osteogenic properties of phenolated alginate (1.2 %) hydrogel containing collagen (0.5 %)/nano-hydroxyapatite (1 %) were studied on human mesenchymal stem cells in vitro. The phenolation rate and physical properties of the hydrogel were assessed using nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), swelling ratio, gelation time, mechanical assay, and degradation rate. The viability of encapsulated cells was monitored on days 7, 14, and 21 using an MTT assay. Osteoblast differentiation was studied using western blotting, and real-time PCR. Using PCR array analysis, the role of the Wnt signaling pathway was also investigated. Data showed that the combination of alginate/collagen/nanohydroxyapatite yielded proper mechanical features. The addition of nanohydroxyapatite, and collagen reduced degradation, swelling rate coincided with increased stiffness. Elasticity and pore size were also diminished. NMR and FTIR revealed suitable incorporation of collagen and nanohydroxyapatite in the structure of alginate. Real-time PCR analysis and western blotting indicated the expression of osteoblast-related genes such as Runx2 and osteocalcin. PCR array revealed the induction of numerous genes related to Wnt signaling pathways during the maturation of human stem cells toward osteoblast-like cells. In vivo data indicated that transplantation of phenolated alginate/collagen/nanohydroxyapatite hydrogel led to enhanced de novo bone formation in rats with critical-sized calvarial defects. Phenolated alginate hydrogel can promote the osteogenic capacity of human amniotic membrane mesenchymal stem cells in the presence of nanohydroxyapatite and collagen via engaging the Wnt signaling pathway.

Recent advances in nano-scaffolds for tissue engineering applications: Toward natural therapeutics

Among the promising methods for repairing or replacing tissue defects in the human body and the hottest research topics in medical science today are regenerative medicine and tissue engineering. On the other hand, nanotechnology has been expanded into different areas of regenerative medicine and tissue engineering due to its essential benefits in improving performance in various fields. Nanotechnology, a helpful strategy in tissue engineering, offers new solutions to unsolved problems. Especially considering the excellent physicochemical properties of nanoscale structures, their application in regenerative medicine has been gradually developed, and a lot of research has been conducted in this field. In this regard, various nanoscale structures, including nanofibers, nanosheets, nanofilms, nano-clays, hollow spheres, and different nanoparticles, have been developed to advance nanotechnology strategies with tissue repair goals. Here, we comprehensively review the application of the mentioned nanostructures in constructing nanocomposite scaffolds for regenerative medicine and tissue engineering. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Diagnostic Tools > Biosensing.

Exosome-bearing hydrogels and cardiac tissue regeneration

BACKGROUND

In recent years, cardiovascular disease in particular myocardial infarction (MI) has become the predominant cause of human disability and mortality in the clinical setting. The restricted capacity of adult cardiomyocytes to proliferate and restore the function of infarcted sites is a challenging issue after the occurrence of MI. The application of stem cells and byproducts such as exosomes (Exos) has paved the way for the alleviation of cardiac tissue injury along with conventional medications in clinics. However, the short lifespan and activation of alloreactive immune cells in response to Exos and stem cells are the main issues in patients with MI. Therefore, there is an urgent demand to develop therapeutic approaches with minimum invasion for the restoration of cardiac function.

MAIN BODY

Here, we focused on recent data associated with the application of Exo-loaded hydrogels in ischemic cardiac tissue. Whether and how the advances in tissue engineering modalities have increased the efficiency of whole-based and byproducts (Exos) therapies under ischemic conditions. The integration of nanotechnology and nanobiology for designing novel smart biomaterials with therapeutic outcomes was highlighted.

CONCLUSION

Hydrogels can provide suitable platforms for the transfer of Exos, small molecules, drugs, and other bioactive factors for direct injection into the damaged myocardium. Future studies should focus on the improvement of physicochemical properties of Exo-bearing hydrogel to translate for the standard treatment options.

Polyurethane-based nanofibrous mat containing porphyrin with photosensitivity and bactericidal properties can promote cutaneous tissue healing in rats

The regeneration of cutaneous tissue is one of the most challenging issues in human regenerative medicine. To date, several studies have been done to promote cutaneous tissue healing with minimum side effects. The healing potential of polyurethane (PU)/Poly (caprolactone)-poly (ethylene glycol)-poly (caprolactone) (PCEC)/chitosan (CS) (PCS) nanofibrous mat with cationic photosensitizer meso tetrakis (N-methyl pyridinium-4-yl) porphyrin tetratosylate salt (TMP) was examined. The CS tripolyphosphate nanoparticles (CSNPs) were prepared and loaded by TMP to provide an efficient drug release system (TMPNPs) for delivery of TMP to promote wound healing. In in vitro setting, parameters such as bactericidal effects, cytocompatibility, and hemolytic effects were examined. The healing potential of prepared nanofibrous mats was investigated in a rat model of full-thickness cutaneous injury. PCS/TMP/TMPNPs nanofibers can efficiently release porphyrin in the aqueous phase. The addition of TMPNPs and CS to the PU backbone increased the hydrophilicity, degradation, and reduced mechanical properties. The culture of human fetal foreskin fibroblasts (HFFF2) on PCS/TMP/TMPNPs scaffold led to an increased survival rate and morphological adaptation analyzed by MTT and SEM images. Irradiation with a red laser (635 nm, 3 J/cm2) for the 30 s reduced viability of S. aureus and E. Coli bacteria plated on PCS/TMP and PCS/TMP/TMPNPs nanofibrous mats compared to PU/PCEC (PC) and PU/PCEC/CS (PCS) groups, indicating prominent antibacterial effects of PCS/TMP and PCS/TMP/TMPNPs nanofibrous (p < 0.05). Data indicated that PCS/TMP/TMPNPs mat enhanced healing of the full-thickness excisional wound in a rat model by the reduction of inflammatory response and fibrotic changes compared to the PC, and PCS groups (p < 0.05). Immunofluorescence imaging indicated that levels of Desmoglein were increased in rats that received PCS/TMP/TMPNPs compared to the other groups. It is found that a PU-based nanofibrous mat is an appropriate scaffold to accelerate the healing of injured skin.

Sandwich-like electro-conductive polyurethane-based gelatin/soybean oil nanofibrous scaffolds with a targeted release of simvastatin for cardiac tissue engineering

Cardiac tissue engineering (CTE) is a promising way for the restoration of injured cardiac tissue in the healthcare system. The development of biodegradable scaffolds with appropriate chemical, electrical, mechanical, and biological properties is an unmet need for the success of CTE. Electrospinning is a versatile technique that has shown potential applications in CTE. Herein, four different types of multifunctional scaffolds, including synthetic-based poly (glycerol sebacate)-polyurethane (PGU), PGU-Soy scaffold, and a series of trilayer scaffolds containing two outer layers of PGU-Soy and a middle (inner) layer of gelatin (G) as a natural and biodegradable macromolecule without simvastatin (S) and with simvastatin (GS), an anti-inflammatory agent, were fabricated in the sandwich-like structure using electrospinning technique. This approach offers a combination of the advantages of both synthetic and natural polymers to enhance the bioactivity and the cell-to-cell and cell-to-matrix intercommunication. An in vitro drug release analysis was performed after the incorporation of soybean oil (Soy) and G. Soy is used as a semiconducting material was introduced to improve the electrical conductivity of nanofibrous scaffolds. The physicochemical properties, contact angle, and biodegradability of the electrospun scaffolds were also assessed. Moreover, the blood compatibility of nanofibrous scaffolds was studied through activated partial thromboplastin time (APTT), prothrombin time (PT), and hemolytic assay. The results showed that all scaffolds exhibited defect-free morphologies with mean fiber diameters in the range of 361 ± 109 to 417 ± 167 nm. A delay in blood clotting was observed, demonstrating the anticoagulant nature of nanofibrous scaffolds. Furthermore, rat cardiomyoblast cell lines (H9C2) were cultured on scaffolds for 7 days, and the morphology and cell arrangement were monitored. Data indicated an appropriate cytocompatibility. Of note, in the PGU-Soy/GS nanofibrous scaffold, a high survival rate was indicated compared to other groups. Our findings exhibited that the simvastatin-loaded polymeric system had positive effects on cardiomyoblasts attachment and growth and could be utilized as a drug release carrier in the field of CTE.

Exosome-loaded microneedle patches: Promising factor delivery route

During the past decades, the advent of different microneedle patch (MNPs) systems paves the way for the targeted and efficient delivery of several growth factors into the injured sites. MNPs consist of several micro-sized (25-1500 μm) needle rows for painless delivery of incorporated therapeutics and increase of regenerative outcomes. Recent data have indicated the multifunctional potential of varied MNP types for clinical applications. Advances in the application of materials and fabrication processes enable researchers and clinicians to apply several MNP types for different purposes such as inflammatory conditions, ischemic disease, metabolic disorders, vaccination, etc. Exosomes (Exos) are one of the most interesting biological bioshuttles that participate in cell-to-cell paracrine interaction with the transfer of signaling biomolecules. These nano-sized particles, ranging from 50 to 150 nm, can exploit several mechanisms to enter the target cells and deliver their cargo into the cytosol. In recent years, both intact and engineered Exos have been increasingly used to accelerate the healing process and restore the function of injured organs. Considering the numerous benefits provided by MNPs, it is logical to hypothesize that the development of MNPs loaded with Exos provides an efficient therapeutic platform for the alleviation of several pathologies. In this review article, the authors collected recent advances in the application of MNP-loaded Exos for therapeutic purposes.

Synthesis and in vitro evaluation of thermosensitive hydrogel scaffolds based on (PNIPAAm-PCL-PEG-PCL-PNIPAAm)/Gelatin and (PCL-PEG-PCL)/Gelatin for use in cartilage tissue engineering

BACKGROUND

Biodegradable thermosensitive hydrogel scaffolds based on novel three-block PCL-PEG-PCL and penta block PNIPAAm-PCL-PEG-PCL-PNIPAAm copolymers blended with gelatin were prepared and examined on functional behavior of chondrocytes.

METHODS

In this work, we compared two different thermosensitive hydrogel scaffolds (PNIPAAm-PCL-PEG-PCL-PNIPAAm)/Gelatin and (PCL-PEG-PCL)/Gelatin prepared by TIPS (thermally induced phase separation) method. The feature of copolymers was characterized by FT-IR, ¹H NMR. The lower critical solution temperatures (LCSTs) of aqueous solutions of copolymers were measured by cloud point (turbidity) measurements. We also examined water absorption capacity and swelling ratio. Mechanical features of the prepared hydrogels were evaluated by stress-strain measurements. Thereafter, isolated chondrocytes were cultured on each scaffold for a period of 10 days and cell arrangement and morphology studied pre-and post-plating. Cell survival assay was done by using MTT assay. The transcription level of genes Sox-9, Collagen-II, COMP, MMP-13 and oligomeric matrix protein was monitored by real-time PCR assay. The samples were also stained by Toluidine blue method to monitor the synthesis of proteoglycan.

RESULTS

Data demonstrated an increased survival rate in cells coated seeded on scaffolds, especially (PNIPAAm-PCL-PEG-PCL-PNIPAAm)/Gelatin as compared to control cells on the plastic surface. (PNIPAAm-PCL-PEG-PCL-PNIPAAm)/Gelatin had potential to increase the expression of genes Sox-6, Collagen-II, COMP and after 10 days in vitro.

CONCLUSION

Thermosensitive PCEC/Gel and (PNIPAAm-PCEC-PNIPAAm)/Gel hydrogel scaffolds that fabricated by TIPS method possesses useful hydrophilic properties for growth and cell embedding and secretion of extracellular matrix. It can serve as an ideal strategy to promote the formation of cartilage tissue.