Daily Cosmetic Research Analysis

OBJECTIVE: The consortium ALT-SPF performed an international round robin test to characterize non-invasive methods as alternatives to the erythema-based testing of sun protection factor (SPF) according to ISO 24444:2019. METHODS: Hybrid diffuse reflectance spectroscopy (HDRS) based on a multi-lambda LED light source uses in vivo reflectance spectra on skin to determine sunscreens in vivo absorbance spectra, which are fused with respective in vitro absorbance spectra measured as thin films transmission as described in ISO 24443:2019. As a part of the ALT-SPF consortium initiative, a blinded study on 64 samples was performed in four European laboratories. After further improvements of the method, a blinded re-evaluation based on 16 samples was performed. Five statistical acceptance criteria for new methods were assessed by an independent statistical institute to compare the obtained results to the reference methods for SPF and UVA-PF. RESULTS: The initial ALT-SPF study 1 showed that the bias criterion was acceptable, while the reproducibility and interlaboratory variability needed further improvement. The re-evaluation study 2 showed that the reproducibility and interlaboratory variability could be considerably improved. Using only n = 10 volunteers and a bias correction based on the initial ALT-SPF study 1 data, the SPF results of the re-evaluation study 2 were close to the acceptance criteria of the ALT-SPF study with criterion 1 (reproducibility) and only 11% over the limit defined by the performance of the gold standard. The UVA-PF results were within the acceptance limits for the acceptance criteria, except criterion 3 being in the 'almost met' range. The re-evaluation study indicates that the method has a comparable precision to the gold standard methods ISO 24444 and ISO 24443. CONCLUSION: This study showed that the LED-HDRS method is capable of providing reasonable non-invasive SPF and UVA-PF results and that the performance shows close alignment to the reference method. Thus, it can be proposed as an alternative method to the current standards ISO 24444 and ISO 24443.

This paper presents the results of the Alt-SPF consortium ring test, obtained by the in-silico methodology, and discusses these results in the context of existing standards. To evaluate the effectiveness of the in-silico methodology in correlating with these standards, a comparison was made between the in-silico sun protection factor (SPF) and the UVA protection factor (UVA-PF) and the values derived by standard in vivo SPF (ISO24444) and in vitro UVA-PF (ISO24443). The model utilises the same algorithm as in vitro measurements of SPF and UVA-PF, with the measured UV transmission substituted by calculated transmission simulated through an applied sunscreen film. The in-silico approach necessitates quantitative UV absorbance data of all UV-filters, their photodegradation and photointeraction properties, oil/water phase synergies and a model describing the irregular distribution of the film thickness on the skin. The performance factors are calculated using an initial analytical evaluation of the 32 test formulations of the ring test, to ascertain the presence and concentration of individual UV absorbers. The filter concentrations obtained are then processed via computational analysis to calculate the SPF and UV-PF values. It has been demonstrated that, in accordance with defined statistical parameters to characterize the ability of a method to correlate with the in vivo SPF standard, the in-silico methodology is a highly reproducible and accurate tool for SPF prediction. The alignment with the lowest measured in vivo SPF values serves to ensure the safety of the end consumer and is not a weakness of the method. Additionally, it has been demonstrated that the methodology facilitates precise prediction of UVA protection in comparison to the in vitro standard ISO 24443. These calculations can be employed to engineer novel sunscreens, thereby diminishing the necessity for ethically questionable and extensive laboratory measurements. In case still in-vivo measurements are needed, the methodology can deliver the frequently required SPF/UVA-PF values and may also support functions such as those of responsible persons, including safety assessors, in their evaluations.

Adipose tissue reconstruction is of significant importance for both cosmetic procedures and therapeutic interventions. Current clinical strategies, including autologous adipose tissue grafting and the application of synthetic materials, still have limitations. Decellularized adipose tissue (DAT) hydrogel in combination with adipose-derived stem cells (ADSCs), has emerged as a superior alternative, because of the abundant sources and inherent adipose regeneration capacity. Nevertheless, the therapeutic potential is constrained by the suboptimal functionality of ADSCs, due to the donor health status, long-term culture, and the post-transplantation environment in vivo. Mitochondria transplantation can enhance the proliferation, migration, differentiation, and pro-angiogenic ability of mesenchymal stem cells, thereby improving the tissue regeneration outcomes. In our research, we developed a novel soft tissue filler, mitochondria transplanted adipose-derived stem cells/decellularized adipose tissue (Mito-ADSCs/DAT) hydrogel. The constructive influence of the Mito-ADSCs/DAT hydrogel to angiogenesis and adipose tissue regeneration was validated in the nude mouse subcutaneous injection model. In vitro experiments and RNA-seq analysis were employed to elucidate the mechanism of Mito-ADSCs in improving adipose tissue regeneration. Although no significant enhancement in adipogenic differentiation was observed in vitro, the Mito-ADSCs exhibited promoted maximal respiration and spare respiratory capacity, and the glycolysis metabolism in Mito-ADSCs increased. Moreover, Mito-ADSCs demonstrated a marked increase in pro-angiogenic capability, which was corroborated by both in vitro assays and RNA-seq analysis. In general, our research demonstrated that the Mito-ADSCs/DAT hydrogel achieved ideal results in adipose tissue regeneration, emerging as a promising soft tissue filler for adipose tissue reconstruction and warranting further investigation for clinical translation.