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Human skin reconstruction on immune-deficient mice has become indispensable for in vivo studies performed in basic research and translational laboratories. Further advancements in making sustainable, prolonged skin equivalents to study new therapeutic interventions rely on reproducible models utilizing patient-derived cells and natural three-dimensional culture conditions mimicking the structure of living skin. Here, we present a novel step-by-step protocol for grafting human skin cells onto immunocompromised mice that requires low starting cell numbers, which is essential when primary patient cells are limited for modeling skin conditions. The core elements of our method are the sequential transplantation of fibroblasts followed by keratinocytes seeded into a fibrin-based hydrogel in a silicone chamber. We optimized the fibrin gel formulation, timing for gel polymerization in vivo, cell culture conditions, and seeding density to make a robust and efficient grafting protocol. Using this approach, we can successfully engraft as few as 1.0 × 106 fresh and 2.0 × 106 frozen-then-thawed keratinocytes per 1.4 cm2 of the wound area. Additionally, it was concluded that a successful layer-by-layer engraftment of skin cells in vivo could be obtained without labor-intensive and costly methodologies such as bioprinting or engineering complex skin equivalents.Key features• Expands upon the conventional skin chamber assay method (Wang et al., 2000) to generate high-quality skin grafts using a minimal number of cultured skin cells.• The proposed approach allows the use of frozen-then-thawed keratinocytes and fibroblasts in surgical procedures.• This system holds promise for evaluating the functionality of skin cells derived from induced pluripotent stem cells and replicating various skin phenotypes.• The entire process, from thawing skin cells to establishing the graft, requires 54 days.Graphical overviewGeneration of a human skin equivalent on an immunodeficient mouse using a fibrin-based grafting system. A schematic of the protocol is shown. Cultured keratinocytes and fibroblasts resuspended in a fibrin-based gel are delivered as layers into a silicon chamber inserted underneath the skin of an immunocompromised mouse. First, a fibrin gel containing encapsulated fibroblasts (up to 2 × 106 per 1.4 cm2 wound) is delivered into the chamber and allowed to solidify for 15 minutes. Second, a fibrin gel containing 1.0–2.0 × 106 keratinocytes is applied on top of the fibroblast layer. On day 7 post-grafting, the chamber is removed, and the wound with the graft is allowed to heal for 4–5 weeks. During healing, a scab forms and eventually falls off. By day 54, the graft is fully established.

Foreign investment is an important economic resource for many countries including Ukraine. The relevance of this study lies in the need to solve problems of attracting foreign investment. The purpose of this study was to consider the conditions for attracting foreign investment in the cyclic imbalances of the world economy. Using the method of correlation-regression analysis, the impact of indicators of financial imbalances was found both in general and by individual sub-indices. The study found the financial imbalances (fiscal, monetary, exchange rate, debt, trade, households, investment, and savings), both present and potential, in the face of the threat of financial and economic crisis. The procedure for assessing financial imbalances in economic activity of the world and their regional groups that implement the process of investment-oriented development was defined. To assess their impact on the volume of foreign direct investment, a comprehensive method of calculating sub-indicators of financial imbalances was proposed, which on the set of certain parameters forms an integrated index of financial imbalances. Methodological approaches to determining the restrictive procedures for the accumulation of financial imbalances associated with the transition of the financial system to a state of financial danger, considering the budget, currency, monetary and debt components were substantiated. The complex method of calculating sub-indicators of financial imbalances in the economy involves the identification of economic risks at the initial stages using the Alert Mechanism on the violation of the balance of the financial and economic systems of the participating countries. Priority areas (real estate and professional services) for attracting foreign investment from around the world were identified. The geostrategic matrix of attraction of foreign investments by the countries of the world was offered

Induced pluripotent stem cells (iPSCs) have potential for regenerative medicine applications, but are generated with very low efficiency. Here, the authors show highly efficient reprogramming of human primary fibroblasts to iPSCs via the synergistic activity of synthetic modified mRNAs, mature miRNA mimics, and optimized culture methods.