Physicochemical features of a cell's microenvironment can exert important effects on cell behavior and include the effects of matrix elasticity on cell differentiation processes, but molecular mechanisms are largely mysterious. Here we highlight recent reports of a mechanical dependence to growth factor activation, with a particular focus on release of TGFβ (Transforming Growth Factor β) from its large latent complex via forced unfolding. We discuss these processes and pathways in the contexts of matrix adhesion and fluid shearing as they might relate to stem cell differentiation and other mechanisms in development, disease, and repair.

Purpose Results following distal hypospadias repair are favorable. Grouping proximal and distal hypospadias repair artificially increases the perceived success rate of proximal hypospadias. We identified our complication rate of proximal hypospadias repair and hypothesized a higher complication rate for 1-stage repair. Materials and Methods We retrospectively reviewed the records of consecutive boys who underwent proximal hypospadias from 2007 to 2014. Proximal hypospadias was defined as a urethral meatus location at or more proximal than the penoscrotal junction after penile degloving. We further stratified boys into those with planned 1-stage vs 2-stage repair. Univariate and Cox regression analyses were performed to assess associations with covariates and compare time to the first complication, respectively. Results A total of 167 boys met study inclusion criteria. Median followup was 31.7 months for 1-stage repair in 86 patients and staged repair in 81. The overall complication rate was 56%. Complications developed in 53 of 86 1-stage (62%) vs 40 of 81 staged (49%) repairs (p = 0.11). The number of unplanned procedures per patient was higher in the 1-stage than in the staged group (0.99 vs 0.69, p = 0.06), as was the number of patients who had at least 2 complications (29 of 86 or 33% vs 13 of 81 or 16%, p = 0.03). Cox regression showed no difference in time to the first complication for staged compared to 1-stage repair (HR 0.77, 95% CI 0.43–1.39). Conclusions Our 56% complication rate of proximal hypospadias warrants further long-term patient followup. More patients in the 1-stage group experienced at least 2 complications. However, when complications developed, they developed no differently in the 2 groups.

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bAvoiding activation of immunity to vector-encoded proteins is critical to the safe and effective use of adeno-associated viral (AAV) vectors for gene therapy. While commonly used serotypes, such as AAV serotypes 1, 2, 7, 8, and 9, are often associated with minimal and/or dysfunctional CD8 ؉ T cell responses in mice, the threshold for immune activation appears to be lower in higher-order species. We have modeled this discrepancy within the mouse by identifying two capsid variants with differential immune activation profiles: AAV serotype 8 (AAV8) and a hybrid between natural rhesus isolates AAVrh32 and AAVrh33 (AAVrh32.33). Here, we aimed to characterize the structural determinants of the AAVrh32.33 capsid that augment cellular immunity to vector-encoded proteins or those of AAV8 that may induce tolerance. We hypothesized that the structural domain responsible for differential immune activation could be mapped to surface-exposed regions of the capsid, such as hypervariable regions (HVRs) I to IX of VP3. To test this, a series of hybrid AAV capsids was constructed by swapping domains between AAV8 and AAVrh32.33. By comparing their ability to generate transgene-specific T cells in vivo versus the stability of transgene expression in the muscle, we confirmed that the functional domain lies within the VP3 portion of the capsid. Our studies were able to exclude the regions of VP3 which are not sufficient for augmenting the cellular immune response, notably, HVRs I, II, and V. We have also identified HVR IV as a region of interest in conferring the efficiency and stability of muscle transduction to AAVrh32.33.