BDNF gene delivery to the retina by cell adhesion peptide-conjugated Gemini Nanoplexes in vivo

Retinal ganglion cell (RGC) neurodegeneration in glaucoma is not prevented by controlling the elevated intraocular pressure alone. Neuroprotective gene therapy approaches could be an essential part of a combination treatment. Five cell adhesion peptide (CAP)-gemini surfactants (18-7 N(p_1-5)-18) were synthesized as building blocks for BDNF gene carrier nanoparticles (CAP-NPXs). The composition of CAP-NPXs was optimized, physicochemically characterized and evaluated for in vitro transfection efficiency (TE) in A7 astrocytes and 3D retinal neurospheres; and for gene expression in vivo in CD1 mice using RFP reporter gene and BDNF levels after intravitreal (IVT) injection. The IgSF-binding 18-7 N(p_FASNKL)-18 pNPXs treated cells demonstrated 1.4-fold higher TE compared to integrin-binding 18-7 N(p_RGD)-18 pNPXs and parent 18-7NH-18 NPXs with overall viability between 86 and 95%. The 18-7 N(p_FASNKL)-18 pNPXs selectively transfected RGCs in 3D MiEye8 neurospheres. In the in vivo CD1 mouse model 18-7 N(p_FASNKL)-18 pNPXs administered by IVT injection delivered tdTomato/BDNF plasmid to retinal cells and produced higher gene expression than the 18-7 N(p_RGD)-18 pNPXs, the parent 18-7NH-18 NPXs and Lipofectamine® 3000 as demonstrated by confocal microscopy of whole mount retinas. The BDNF gene expression, assessed by ELISA, showed significantly high levels of BDNF with 18-7 N(p_FASNKL)-18 (422.60 ± 42.60 pg/eye), followed by 18-7 N(p_RGD)-18 pNPXs (230.62 ± 24.47 pg/eye), 18-7NH-18 NPXs (245.90 ± 39.72 pg/eye), Lipofectamine® 3000 (199.99 ± 29.90 pg/eye) and untreated controls (131.33 ± 20.30 pg/eye). In sum, the 18-7 N(p_FASNKL)-18 pNPXs induced 3.4-fold higher BDNF level compared to controls and 2-fold higher than 18-7 N(p_RGD)-18 pNPXs. The in vivo efficacy of 18-7 N(p_FASNKL)-18 NPXs to produce BDNF levels at pharmacologically relevant levels supports further studies.

Co-immobilization of ACH11 antithrombotic peptide and CAG cell-adhesive peptide onto vascular grafts for improved hemocompatibility and endothelialization

Surface modification by conjugating biomolecules has been widely proved to enhance biocompatibility of small-caliber artificial vascular grafts. In this study, we aimed at developing a multifunctional vascular graft that provides not only good hemocompatibility but also in situ rapid endothelialization. Herein, a vascular graft (inner diameter ∼2 mm) was fabricated by electrospinning with poly(lactic acid-co-caprolactone) and gelatin, and then biofunctionalized with antithrombotic peptide with sequence LTFPRIVFVLG (ACH₁₁) and cell adhesion peptide with sequence CAG through adhesive poly(dopamine) coating. We developed this graft with the synergistic properties of low thrombogenicity and rapid endothelialization. The successful grafting of both CAG and ACH₁₁ peptides was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface micromorphology of the modified surfaces was observed by field emission scanning electron microscopy. Our results demonstrated that the multifunctional surface suppressed the denaturation of absorbed fibrinogen, hindered coagulation factor Xa activation, and inhibited platelet adhesion and aggregation. Importantly, this modified surface could selectively enhance endothelial cells adhesion, proliferation and release of nitric oxide. Upon in vivo implantation of 6 weeks, the multifunctional vascular graft showed improved patency and superior vascular endothelialization. Overall, the results effectively demonstrated that the co-immobilization of ACH₁₁ and CAG provided a promising method for the improvement of hemocompatibility and endothelialization of vascular grafts. STATEMENT OF SIGNIFICANCE: Electrospun small-caliber vascular grafts are increasingly used to treat cardiovascular diseases. Despite their success related to their good biodegradation and mechanical strength, they have some drawbacks, such as low hemocompatibility and endothelialization. The single-function ligands are insufficient to modify surface with both good hemocompatibility and rapid endothelialization simultaneously. Therefore, we functionalized electrospun vascular graft by novel antithrombotic peptide and cell-adhesive peptide to construct superior anticoagulation and ECs-selective adhesion surface in present study. The multifunctional vascular grafts benefit for high long-term patency and rapid endothelialization.

Effects of cell adhesion motif, fiber stiffness, and cyclic strain on tenocyte gene expression in a tendon mimetic fiber composite hydrogel

We recently developed a fiber composite consisting of tenocytes seeded onto discontinuous fibers embedded within a hydrogel, designed to mimic physiological tendon micromechanics of tension and shear. This study examined if cell adhesion peptide (DGEA or YRGDS), fiber modulus (50 or 1300 kPa) and/or cyclic strain (5% strain, 1 Hz) influenced bovine tenocyte gene expression. Ten genes were analyzed and none were sensitive to peptide or fiber modulus in the absence of cyclic tensile strain. Genes associated with tendon (SCX and TNMD), collagens (COL1A1, COL3A1, COL11A1), and matrix remodelling (MMP1, MMP2, and TIMP3) were insensitive to cyclic strain. Contrarily, cyclic strain up-regulated IL6 by 30-fold and MMP3 by 10-fold in soft YRGDS fibers. IL6 expression in soft YRGDS fibers was 5.7 and 3.3-fold greater than in soft DGEA fibers and stiff RGD fibers, respectively, under cyclic strain. Our findings suggest that changes in the surrounding matrix can influence catabolic genes in tenocytes when cultured in a complex strain environment mimicking that of tendon, while having minimal effects on tendon and homeostatic genes.

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A fiber composite material exhibits multimodal shear and tension micromechanics.

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Gene expression of tenocytes is insensitive to fiber stiffness or YRGDS vs DGEA.

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Tendon marker and collagen genes are insensitive to fiber environment under strain.

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MMP3 and IL6 genes are sensitive to fiber stiffness and peptide under cyclic strain.

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Healthy tenocytes rapidly respond to their environment by a catabolic response.