Reduced mosquito survival in metal-roof houses may contribute to a decline in malaria transmission in sub-Saharan Africa.

In The Gambia, metal-roof houses were hotter during the day than thatched-roof houses. After 24 h, the mortality of Anopheles gambiae, the principal African malaria vector, was 38% higher in metal-roof houses than thatched ones. During the day, mosquitoes in metal-roof houses moved from the hot roof to cooler places near the floor, where the temperature was still high, reaching 35 °C. In laboratory studies, at 35 °C few mosquitoes survived 10 days, the minimum period required for malaria parasite development. Analysis of epidemiological data showed there was less malaria and lower vector survival rates in Gambian villages with a higher proportion of metal roofs. Our findings are consistent with the hypothesis that the indoor climate of metal-roof houses, with higher temperatures and lower humidity, reduces survivorship of indoor-resting mosquitoes and may have contributed to the observed reduction in malaria burden in parts of sub-Saharan Africa.

Soliciting strategies for developing cell-based reference materials to advance mesenchymal stromal cell research and clinical translation.

The mesenchymal stromal cell (MSC) field continues to rapidly progress with a number of clinical trials initiated and completed, with some reported successes in multiple clinical indications, and a growing number of companies established. The field, nevertheless, faces several challenges. Persistent issues include the definition of a MSC and comparability between MSC preparations. This is because of inherent cell heterogeneity, the absence of markers that are unique to MSCs, and the difficulty in precisely defining them by developmental origin. Differences in the properties of MSCs also depend on the site of tissue harvest, phenotypic and genotypic characteristics of the donor and the isolation, and storage and expansion methods used. These differences may be sufficient to ensure that attributes of the final MSC product could differ in potentially significant ways. Since there are currently no gold standards, we propose using a reference material to establish methods of comparability among MSC preparations. We suggest four possible "ruler scenarios" and a method for global distribution. We further suggest that critical to establishing a reference material is the need to define protocols for comparing cells. The main purpose of this article is to solicit input in establishing a consensus-based comparison. A comparative approach will be critical to all stages of translation to better clarify mechanisms of MSC actions, define an optimal cell manufacturing process, ensure best practice clinical investigations, extend the use of an MSC product for new indications, protect an MSC product from imitators, and develop uniform reimbursement policies. Importantly, a reference material may enable a consensus on a practical definition of MSCs.