Display of the Albumin-Binding Domain in the Envelope Improves Lentiviral Vector Bioavailability.

Vesicular stomatitis virus G glycoprotein (VSVg) is extensively used for retroviral and lentiviral vector (LV) pseudotyping. However, VSVg pseudotyped vectors are serum inactivated, blocking the in vivo gene delivery. Several strategies have been employed to prevent complement inactivation, including chemical and genetic envelope modifications. This study employed the streptococcal albumin-binding domain (ABD) to generate a construct to express ABD as a glycosylphosphatidylinositol-anchored protein. LV particles bearing ABD are able to bind bovine and human serum albumin in vitro. Neither the lentiviral vector production titer nor the in vitro transduction was affected by the ABD display. The study demonstrated that ABD-bearing LVs are protected from human complement inactivation. More importantly, intravenous administration demonstrated that the presence of ABD significantly reduces lentivector sequestration in liver and bone-marrow cells. Therefore, the use of ABD represents an improvement for in vivo gene therapy applications. The results strongly point to ABD display as a universal strategy to increase the in vivo efficacy of different viral vectors.

Immune-Regulatory Molecule CD69 Controls Peritoneal Fibrosis.

Patients with ESRD undergoing peritoneal dialysis develop progressive peritoneal fibrosis, which may lead to technique failure. Recent data point to Th17-mediated inflammation as a key contributor in peritoneal damage. The leukocyte antigen CD69 modulates the setting and progression of autoimmune and inflammatory diseases by controlling the balance between Th17 and regulatory T cells (Tregs). However, the relevance of CD69 in tissue fibrosis remains largely unknown. Thus, we explored the role of CD69 in fibroproliferative responses using a mouse model of peritoneal fibrosis induced by dialysis fluid exposure under either normal or uremic status. We found that cd69-/- mice compared with wild-type (WT) mice showed enhanced fibrosis, mesothelial to mesenchymal transition, IL-17 production, and Th17 cell infiltration in response to dialysis fluid treatment. Uremia contributed partially to peritoneal inflammatory and fibrotic responses. Additionally, antibody-mediated CD69 blockade in WT mice mimicked the fibrotic response of cd69-/- mice. Finally, IL-17 blockade in cd69-/- mice decreased peritoneal fibrosis to the WT levels, and mixed bone marrow from cd69-/- and Rag2-/-γc-/- mice transplanted into WT mice reproduced the severity of the response to dialysis fluid observed in cd69-/- mice, showing that CD69 exerts its regulatory function within the lymphocyte compartment. Overall, our results indicate that CD69 controls tissue fibrosis by regulating Th17-mediated inflammation.

Biomechanical remodeling of the microenvironment by stromal caveolin-1 favors tumor invasion and metastasis.

Mechanotransduction is a key determinant of tissue homeostasis and tumor progression. It is driven by intercellular adhesions, cell contractility, and forces generated within the microenvironment and is dependent on extracellular matrix composition, organization, and compliance. We show that caveolin-1 (Cav1) favors cell elongation in three-dimensional cultures and promotes Rho- and force-dependent contraction, matrix alignment, and microenvironment stiffening through regulation of p190RhoGAP. In turn, microenvironment remodeling by Cav1 fibroblasts forces cell elongation. Cav1-deficient mice have disorganized stromal tissue architecture. Stroma associated with human carcinomas and melanoma metastases is enriched in Cav1-expressing carcinoma-associated fibroblasts (CAFs). Cav1 expression in breast CAFs correlates with low survival, and Cav1 depletion in CAFs decreases CAF contractility. Consistently, fibroblast expression of Cav1, through p190RhoGAP regulation, favors directional migration and invasiveness of carcinoma cells in vitro. In vivo, stromal Cav1 remodels peri- and intratumoral microenvironments to facilitate tumor invasion, correlating with increased metastatic potency. Thus, Cav1 modulates tissue responses through force-dependent architectural regulation of the microenvironment.

An adult myometrial pluripotential precursor that promotes healing of damaged muscular tissues.

The use of adult stem cells for tissue and organ regeneration constitutes a promising alternative therapy in many human diseases that are currently not treatable. We have isolated a new cell type from mouse adult uterine biopsies (murine adult myometrial precursors or mAMPs) by means of using a simple and non-invasive approach. These cells have been characterized by surface markers, being positive for CD31, CD34, CD44, CD117, Stro-1 and Sca-1. A similar cell population (hAMPs) was isolated from human biopsies. AMPs can differentiate in vitro into a number of mesodermal (smooth and skeletal muscle, osteoblasts and adipocytes) as well as epidermal lineages (all neural lineages). AMPs are unusual adult stem cells as they still express some embryonic antigens and remain undifferentiated through a high number of passages before entering senescence. Importantly, when injected into animal models of muscular disease, AMPs can regenerate new muscle fibers, and promote functional muscular recovery. Moreover, these cells can regenerate the uterine lining after wound healing, reconstructing the uterine muscular architecture. In addition, these cells can form new vessels both in vitro and in vivo. We believe that these cells have superior features to other known adult stem cells and, consequently, their use holds great promise for regenerative medicine, drug development and basic research.