Modified gelatin hydrogel nonwoven fabrics (Genocel) as a skin substitute in murine skin defects.

Introduction: From previous research, an emerging material composed of gelatin hydrogel nonwoven fabric (Genocel) has shown potential as a skin substitute, by improving neovascularization promotion in the early phase of wound healing. However, Genocel was inferior in terms of granulation formation compared to Pelnac. To solve this problem, we modified the manufacturing process of Genocel to reduce its water content, extend the degradation time (Genocel-L), and evaluate its healing process as a skin substitute. Methods: Genocel with a low water content (Genocel-L) was prepared and the difference in water content compared to that of the conventional Genocel was confirmed. Degradation tests were performed using collagenase and compared among Genocel-L, Genocel, and Pelnac sheets. In the in vivo study, sheets of Genocel-L or Pelnac were applied to skin defects created on the backs of C57BL/6JJcl mice. On days 7, 14, and 21, the remaining wound area was evaluated and specimens were harvested for Hematoxylin and Eosin, Azan, anti-CD31, CD68, and CD163 staining to assess neoepithelialization, granulation tissue, capillary formation, and macrophage infiltration. Results: Genocel-L had a lower water content than the conventional Genocel and a slower degradation than Genocel and Pelnac. In the in vivo experiment, no significant differences were observed between Genocel-L and Pelnac in relation to the wound area, neoepithelium length, granulation formation, and the number of newly formed capillaries. The area of newly formed capillaries in the Pelnac group was significantly larger than that in the Genocel-L group on day 21 (p < 0.05). Regarding macrophage infiltration, significantly more M2 macrophages were induced in the Pelnac group on days 14 and 21, and the M2 ratio was larger in the Pelnac group (p < 0.05) during the entire process. Conclusions: Genocel-L has a lower water content and slower degradation rate than the conventional Genocel. Genocel-L had equivalent efficacy as a skin substitute to Pelnac, and can therefore be considered feasible for use as a skin substitute. However, a manufacturing method that can further modify Genocel-L is required to recover its early angiogenic potential.

An improved synthesis of 2'-O,4'-C-ethylene nucleic acid (ENA) and thermodynamic studies of duplex formation containing the guanosine ENA unit.

Oligonucleotides containing 2'-O,4'-C-ethylene nucleic acids (ENA) have been proven highly effective for antisense therapeutics. 2'-O,4'-C-Ethyleneguanosine and its phosphoramidite were previously obtained from 3,5-di-O-benzy1-4-C-(p-tolulenesulfonyloxyethyl)-1,2-di-O-acetyl-α-D-erythropentofuranose by glycosylation, but with limited efficiency. Using 3,5-di-O-benzy1-4-C-(2-t-butyldiphenylsilyloxyethyl)-1,2-di-O-acetyl-α-D-erythropentofuranose as an alternative substrate, we developed several methods to obtain 2'-O,4'-C-ethyleneguanosine derivatives with much higher yields than previously reported. These methods were also applicable for the synthesis of 2'-O,4'-C-ethyleneadenosine and 2'-O,4'-C-ethylene-5-methyluridine derivatives. Moreover, we investigated the thermodynamic benefit of DNA strands containing 2'-O,4'-C-ethyleneguanosines during duplex formation with complementary RNA. Only a single modification by the nucleoside resulted in a 10-fold greater binding constant of the DNA/RNA duplex.

Enhancement of exon skipping activity by reduction in the secondary structure content of LNA-based splice-switching oligonucleotides.

PAGE and UV melting analysis revealed that longer LNA-based splice-switching oligonucleotides (SSOs) formed secondary structures by themselves, reducing their effective concentration. To avoid such secondary structure formation, we introduced 7-deaza-2'-deoxyguanosine or 2'-deoxyinosine into the SSOs. These modified SSOs, with fewer secondary structures, showed higher exon skipping activities.