Elucidation of mechanisms that regulate hematopoietic stem cell self-renewal and differentiation would be facilitated by the identification of defined culture conditions that allow these cells to be amplified. We now demonstrate a significant net increase (3-fold, P < 0.001 )

The Internet has emerged as an important tool for the delivery of health promotion and disease prevention interventions. Our community-based participatory research (CBPR) partnership developed and piloted CyBER/testing, a culturally congruent intervention designed to promote HIV testing among men who have sex with men (MSM) within existing Internet chat rooms. Using a quasi-experimental, single-group study design, cross-sectional data were collected from chat room participants, known as “chatters,” at pretest (n=346) and post-test (n=315). Extant profile data also were collected to describe the demographics of the online population. The intervention significantly increased self-reported HIV testing among chatters overall, increasing rates from 44.5% at pretest to nearly 60% at post-test (p<.001). Furthermore, chatters who reported having both male and female sexual partners had nearly 6 times the odds of reporting HIV testing at post-test. Findings suggest that chat room-based HIV testing intervention may increase testing among MSM who may be difficult to reach in traditional physical spaces.

Previous studies have demonstrated hematopoietic stem cell amplification in vitro after the activation of three cell-surface receptors: flt3͞flk2, c-kit, and gp130. We now show flt3-ligand and Steel factor alone will stimulate >85% of c-kit ؉ Sca-1 ؉ lin ؊ adult mouse bone marrow cells to proliferate in single-cell serum-free cultures, but concomitant retention of their stem cell activity requires additional exposure to a ligand that will activate gp130. Moreover, this response is restricted to a narrow range of gp130-activating ligand concentrations, above and below which hematopoietic stem cell activity is lost. These findings indicate a unique contribution of gp130 signaling to the maintenance of hematopoietic stem cell function when these cells are stimulated to divide with additional differential effects dictated by the intensity of gp130 activation.IL-6 ͉ serum-free culture

This study is the first published multi-app study, of which we are aware, to evaluate both the acceptability and feasibility of providing sexual health information and HIV/STD testing referrals via established geosocial and sexual networking apps for MSM. Data were collected using an online survey and through four apps (A4A Radar, Grindr, Jack’d, and Scruff). Two-thirds (64%) found apps to be an acceptable source for sexual health information. MSM who found apps as acceptable were more likely non-white men, not sure of their current HIV status, and have low HIV testing self-efficacy. One-quarter (26%) of informational chats with the health educator resulted in users requesting and being referred to local HIV/STD testing sites. There were significant differences in the number and types of interactions across apps. Established apps for MSM may be both an acceptable and feasible platform to promote HIV/STD testing. Future research should evaluate interventions that leverage this technology.

Recent studies have identified thrombopoietin (TPO), flt-3 ligand (FL), Steel factor (SF), and interleukin-11 (IL-11) as cytokines able to stimulate amplification of the most primitive murine hematopoietic cells in vitro. However, dose-response and interaction parameters that predict how to optimize mixtures of these cytokines have not been previously defined. To obtain this information, Sca-1(+)lin(-) and c-kit(+)Sca-1(+)lin(-) adult mouse bone marrow cells were cultured for 10 and 14 days, respectively, in serum-free medium with varying concentrations of these cytokines. Quantitative assays were performed to determine the influences of the cytokine combinations tested on changes in long-term repopulating hematopoietic stem cells (HSCs), in vitro colony-forming cells (CFCs), and total cell numbers. A two-level factorial design was first used to screen the effects of TPO, SF, FL, and IL-11 as well as two different incubation temperatures. IL-11 and SF were found to be the most significant stimulators of murine HSC expansion. More detailed analyses of the effects on c-kit(+)Sca-1(+)lin(-) cells of IL-11, SF, and FL concentrations and their interactions using response surface methodology showed IL-11 to have a maximal stimulatory effect on HSC expansion at 20 ng/mL with higher concentrations being inhibitory. In contrast, not even high concentration saturation of the effects of either SF or FL was observed as the stimulatory effect of both SF and FL increased beyond 300 ng/mL. A negative interaction between SF and FL on HSCs was discovered. Interestingly, a generally similar pattern of cytokine effects was found to influence the 14-day output of CFCs and total cells from the same c-kit(+)Sca-1(+)lin(-) starting cell population. However, compared with HSCs, the cytokine requirements for maximizing the generation of CFCs and total cells were at much lower cytokine doses. From the information provided by the factorial analysis, mathematical models based on Monod kinetics for inhibitory substrates were developed that allow total cell, CFC, and HSC expansion to be predicted as a function of the IL-11, SF, and FL concentrations in terms of more widely recognized parameters. Overall, these methods should also serve as a guide for the future design and testing of other ex vivo stem cell expansion systems.