Diabetic
wounds are a worldwide health problem causing extremely
heavy public health burden and require effective treatment. Optimal strategies
for treating nonhealing diabetic wounds include stem-cell-based therapy
and delivery of novel drug substances, such as functional microRNAs
(miRNAs); however, miRNA easily degrades in the wound microenvironment.
Herein, we developed a human adipose stem-cell-derived exosome (hASC-exos)-based
miRNA delivery strategy to enhance its therapeutic efficacy. The miR-21-5p
mimics, as novel therapeutic candidates for diabetic wounds, were
loaded into hASC-exos by electroporation, taking advantage of natural
availability and biocompatibility of exosomes as extracellular miRNA
transporting particles. The engineered exosomes (E-exos) exhibited
excellent effects on promoting proliferation and migration of keratinocytes
via Wnt/β-catenin signaling in vitro and accelerating diabetic
wound healing by increasing re-epithelialization, collagen remodeling,
angiogenesis, and vessel maturation in vivo. Results from this study
would set the fundamentals of applying hASC-exos to deliver future
drug substances and to develop cell-free therapy for wound-healing
treatments.
Bioadhesive microporous architectures
that mimic the functions
of a natural extracellular matrix (ECM) were prepared by self-assembling
polydopamine (PDA) microcapsules, which not only favor cell adhesion
and growth, but also facilitate growth factor immobilization and release.
PDA-coated polystyrene (PS) microspheres are synthesized by polymerization
of dopamine on sulfonated PS microspheres and then assembled using
positively charged chitosan (CHI) layers as link agents. After the
PS core templates were removed, microporous architectures composed
of PDA microcapsules were obtained. The produced microporous PDA architectures
have a high capability of adsorbing BMP-2 and realize the sustained
release of BMP-2. More importantly, the bioadhesive micro architecture
and its immobilized BMP-2 synergistically enhance the activity and
osteogenetic differentiation of bone marrow mesenchymal stem cells
(BMSCs). Both supercell adhesion and BMP-2 immobilization ability
of these architectures are attributed to the intrinsic adhesive nature
of PDA and the porous architectures via the assembly of PDA microcapsules.
The bioadhesive microporous PDA architectures with both cell affinitive
and GF release features have a great potential to mimic natural ECM
for modifying various medical devices in the fields of tissue engineering
and regenerative medicine.
A novel shear-thinning hybrid bioink with good printability, mechanical support, biocompatibility, and bioactivity was developed by combining gellan gum, sodium alginate, and thixotropic magnesium phosphate-based gel (GG–SA/TMP-BG).
Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we employed pulsed electrochemical deposition to co-deposit HA and Ag simultaneously, which realized the uniform distribution of Ag particles in the coatings. This method was based on the use of a well-designed electrolyte containing Ag ions, calcium ions and L-cysteine, in which cysteine acted as the coordination agent to stabilize Ag ions. The antibacterial and cell culture tests were used to evaluate the antibacterial properties and biocompatibility of HA/Ag composite coatings, respectively. The results indicated the as-prepared coatings had good antibacterial properties and biocompatibility. However, an appropriate silver content should be chosen to balance the biocompatibility and antibacterial properties. Heat treatments promoted the adhesive strength and enhanced the biocompatibility without sacrificing the antibacterial properties of the HA/Ag coatings. In summary, this study provided an alternative method to prepare bioactive surfaces with bactericidal ability for biomedical devices.
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