Exosomes are required for the regenerative effects of human cardiosphere-derived cells (CDCs). Studies show that they mimic the cardioprotective benefits of CDCs in rodents and porcine myocardial infarction (MI) models. Hypoxic preconditioning of stem cells increases the cardioprotective effects of exosomes in MI models by enhancing angiogenesis. Several exosomal microRNAs (miRNAs) up-regulate in response to hypoxia and play a role in cardioprotective and pro-angiogenic effects. In this study, we have demonstrated that human CDCs secreted exosomes under hypoxic conditions (1% O for 2 days) enhanced tube formation by human umbilical vein endothelial cells (HUVECs) at a concentration of 25 µg/mL. Pro-angiogenic exosomal miRNAs including miR-126, miR-130a, and miR-210 showed a substantial increase (>2-, >2-, and >4-fold, respectively) in the hypoxic exosomes compared to normoxic CDC-derived exosomes. Our study suggested a significant benefit of hypoxic CDC exosomes for the treatment of cardiac diseases by induction of angiogenesis via enrichment of pro-angiogenic exosomal miRNAs.
The nanofibrous structure containing protein and polysaccharide has good potential in tissue engineering. The present work aims to study the role of chitosan in gelatin/chitosan nanofibrous scaffolds fabricated through electrospinning process under optimized condition. The performance of chitosan in gelatin/chitosan nanofibrous scaffolds was evaluated by mechanical tests, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and in vitro cell culture on scaffolds with different gelatin/chitosan blend ratios. To assay the influence of chitosan ratio on biocompatibility of the electrospun gelatin/chitosan scaffolds for skin tissue engineering, the culturing of the human dermal fibroblast cells (HDF) on nanofibers in terms of attachment, morphology and proliferation was evaluated. Morphological observation showed that HDF cells were attached and spread well on highly porous gelatin/chitosan nanofibrous scaffolds displaying spindle-like shapes and stretching. The fibrous morphologies of electrospun gelatin/chitosan scaffolds in culture medium were maintained during 7 days. Cell proliferation on electrospun gelatin/chitosan scaffolds was quantified by MTS assay, which revealed the positive effect of chitosan content (around 30%) as well as the nanofibrous structure on the biocompatibility (cell proliferation and attachment) of substrates.Graphical abstract
Risk factors of nonhealing
wounds include persistent bacterial
infections and rapid onset of dehydration; therefore, wound dressings
should be used to accelerate the healing process by helping to disinfect
the wound bed and provide moisture. Herein, we introduce a transparent
tributylammonium alginate surface-modified cationic polyurethane (CPU)
wound dressing, which is appropriate for full-thickness wounds. We
studied the physicochemical properties of the dressing using Fourier
transform infrared, 1H NMR, and 13C NMR spectroscopies
and scanning electron microscopy, energy-dispersive X-ray, and thermomechanical
analyses. The surface-modified polyurethane demonstrated improved
hydrophilicity and tensile Young’s modulus that approximated
natural skin, which was in the range of 1.5–3 MPa. Cell viability
and in vitro wound closure, assessed by MTS and the scratch assay,
confirmed that the dressing was cytocompatible and possessed fibroblast
migratory-promoting activity. The surface-modified CPU had up to 100%
antibacterial activity against Staphylococcus aureus and Escherichia coli as Gram-positive
and Gram-negative bacteria, respectively. In vivo assessments of both
noninfected and infected wounds revealed that the surface-modified
CPU dressing resulted in a faster healing rate because it reduced
the persistent inflammatory phase, enhanced collagen deposition, and
improved the formation of mature blood vessels when compared with
CPU and commercial Tegaderm wound dressing.
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