RelCoVax®, a two antigen subunit protein vaccine candidate against SARS-CoV-2 induces strong immune responses in mice.

The COVID-19 pandemic has spurred an unprecedented movement to develop safe and effective vaccines against the SARS-CoV-2 virus to immunize the global population. The first set of vaccine candidates that received emergency use authorization targeted the spike (S) glycoprotein of the SARS-CoV-2 virus that enables virus entry into cells via the receptor binding domain (RBD). Recently, multiple variants of SARS-CoV-2 have emerged with mutations in S protein and the ability to evade neutralizing antibodies in vaccinated individuals. We have developed a dual RBD and nucleocapsid (N) subunit protein vaccine candidate named RelCoVax® through heterologous expression in mammalian cells (RBD) and E. coli (N). The RelCoVax® formulation containing a combination of aluminum hydroxide (alum) and a synthetic CpG oligonucleotide as adjuvants elicited high antibody titers against RBD and N proteins in mice after a prime and boost dose regimen administered 2 weeks apart. The vaccine also stimulated cellular immune responses with a potential Th1 bias as evidenced by increased IFN-γ release by splenocytes from immunized mice upon antigen exposure particularly N protein. Finally, the serum of mice immunized with RelCoVax® demonstrated the ability to neutralize two different SARS-CoV-2 viral strains in vitro including the Delta strain that has become dominant in many regions of the world and can evade vaccine induced neutralizing antibodies. These results warrant further evaluation of RelCoVax® through advanced studies and contribute towards enhancing our understanding of multicomponent subunit vaccine candidates against SARS-CoV-2.

Paracrine factors secreted by umbilical cord-derived mesenchymal stem cells induce angiogenesis in vitro by a VEGF-independent pathway.

Improvement in angiogenesis using mesenchymal stem cells (MSCs) is evolving as an option in patients with vascular insufficiencies. The paracrine factors secreted by MSCs have been attributed to the angiogenic response. This study was conducted to identify the factors secreted by umbilical cord-derived MSCs (UCMSCs) that might play a role in angiogenesis. To this aim, we evaluated the presence of well known proangiogenic factors in the conditioned media (CM) derived from UCMSCs by ELISA. While vascular endothelial growth factor (VEGF), a well known angiogenic factor, was not detected in the CM, gene expression was nevertheless detected in these cells. Further investigations revealed the presence of soluble VEGF receptors (sVEGF-R1 and R2) that were capable of neutralizing exogenous VEGF. Human umbilical cord vein-derived endothelial cells exposed in vitro to CM, in comparison to control media, showed improved migration (P<0.007) and capillary-like network formation (P<0.001) with no significant change in endothelial cell proliferation. The angiogenic response observed with the paracrine factors secreted by UCMSC could be due to the presence of significant levels of a metalloprotease and matrix metalloproteases-2 (237.4±47.1 ng/10(6) cells). Data suggest that a VEGF-independent pathway is involved in the angiogenic response observed with endothelial cells in the presence of UCMSC-CM.

Efficacy and safety of autologous cultured melanocytes delivered on poly (DL-lactic acid) film: a prospective, open-label, randomized, multicenter study.

BACKGROUND: Small vitiliginous patches have been treated with epidermal grafts or their cell suspensions. In an attempt to overcome some of the shortcomings of cell suspension delivery, we have delivered melanocytes on a polymeric film. OBJECTIVES: To evaluate the clinical effectiveness of a cultured graft consisting of autologous cultured melanocytes on a poly (DL-lactic acid) (PLA) film in subjects with stable vitiligo. METHODS: A prospective open-label, randomized, multicenter clinical trial was conducted with 22 patients. Each subject was treated with cultured graft and polyurethane dressing (control arm) after epidermal ablation and followed for up to 9 months. The extent of repigmentation in the treated sites was compared with that control sites at days 90, 180, and 270. RESULTS: In the treatment arm, a minimum of 70% repigmentation was observed in five subjects at day 90; nine at day 180, and 10 at day 270. In the control arm, only one subject showed repigmentation until day 270. None of the test sites reported any recurrence of vitiliginous patches by the end of the study. CONCLUSIONS: Cultured melanocytes delivered on PLA film were efficacious and safe when applied on patients with stable vitiligo.

A novel dermal tissue construct: development and in vitro characterization.

A dermal tissue construct composed of human dermal fibroblasts and a chitosan sponge has been developed, targeted towards the treatment of diabetic nonhealing ulcers. The construct has been designed in a way that the dermal fibroblasts are arranged as a three-dimensional sheet adhered entirely on one side of the chitosan sponge. This design would allow maximal diffusion of growth factors from the cells to the wound bed when the construct is applied on the wound with the cellular sheet side making contact with the wound bed. The diffusion of secreted growth factors would take place directly from cells to the wound bed without being impeded by a matrix. The cells are present at a high density in the dermal construct, which would aid in accelerated wound healing. The construct has a porous chitosan sponge base, which would allow gas exchange, and renders the dermal construct very flexible so that it would take the shape of the wound contours well, while having mechanical integrity. The viability of cells in the construct is greater than 90%. The dermal construct produces a high amount of vascular endothelial growth factor, from 42 ng to 31 ng in 24 h. The construct also produces high amounts of Interleukin-8 (IL-8), from 375 ng to 1065 ng in the first 24 h. Both VEGF and IL-8 have important roles in the healing of chronic diabetic ulcers.

Cultured melanocytes: from skin biopsy to transplantation.

Restoration of cutaneous pigmentation has been achieved in stable vitiligo by autologous melanocyte transplantation. This study was aimed to develop a methodology to deliver melanocytes to vitiliginous area following their processing and culture in a centralized facility. Here we report a methodology to culture melanocytes on carrier films, transport the cells, and graft them on vitiliginous areas. The salient features of this study include: 1) development of polylactic acid (PLA) films that support melanocyte attachment, growth, and delivery; 2) establish transport conditions for skin biopsies from hospitals; 3) establish transport conditions for cultured cells from cell processing center to hospitals. Results suggest that PLA films could serve as carriers for melanocytes during transport. "Upside-down" application of the graft results in the migration of cells from the films into the dermabraded area. The transport conditions ensure cell viability for 96 h. This system could help clinicians, who do not have access to cell culture facilities, transplant cultured melanocytes in a cost-effective manner.