Core-Shell Pure Collagen Threads Extruded from Highly Concentrated Solutions Promote Colonization and Differentiation of C3H10T1/2 Cells.

The elaboration of scaffolds able to efficiently promote cell differentiation toward a given cell type remains challenging. Here, we engineered dense type I collagen threads with the aim of providing scaffolds with specific morphological and mechanical properties for C3H10T1/2 mesenchymal stem cells. Extrusion of pure collagen solutions at different concentrations (15, 30, and 60 mg/mL) in a PBS 5× buffer generated dense fibrillated collagen threads. For the two highest concentrations, threads displayed a core-shell structure with a marked fibril orientation of the outer layer along the longitudinal axis of the threads. Young's modulus and ultimate tensile stress as high as 1 and 0.3 MPa, respectively, were obtained for the most concentrated collagen threads without addition of any cross-linkers. C3H10T1/2 cells oriented themselves with a mean angle of 15-24° with respect to the longitudinal axis of the threads. Cells penetrated the 30 mg/mL scaffolds but remained on the surface of the 60 mg/mL ones. After three weeks of culture, cells displayed strong expression of the tendon differentiation marker Tnmd, especially for the 30 mg/mL threads. These results suggest that both the morphological and mechanical characteristics of collagen threads are key factors in promoting C3H10T1/2 differentiation into tenocytes, offering promising levers to optimize tissue engineering scaffolds for tendon regeneration.

Differentiation of neural-type cells on multi-scale ordered collagen-silica bionanocomposites.

Cells respond to biophysical and biochemical signals. We developed a composite filament from collagen and silica particles modified to interact with collagen and/or present a laminin epitope (IKVAV) crucial for cell-matrix adhesion and signal transduction. This combines scaffolding and signaling and shows that local tuning of collagen organization enhances cell differentiation.

From Tendon Injury to Collagen-based Tendon Regeneration: Overview and Recent Advances.

Tendon injury is a clinical, societal and economical issue. Moreover, tendon repair represents an important clinical challenge, partly due to the mechanical constraints that occur at the junctions with muscle and bone. Several strategies have been developed for tendon repair. In this review, we first assess the importance of tendon injuries from different sites and their causes. After a short overview of tendon three-dimensional organization, the complexity of the perfect repair quest is presented ranging from current clinical procedures to new engineering scaffolds. We then sum up tendon engineering requirements and focus on new collagen-based scaffolds, which raise promising prospects to mimic and repair tendon. In particular, we survey quantitatively a large panel of techniques to produce these scaffolds, detailing their principle and recent improvements.

High Prevalence of Opaline Silica in Urinary Stones From Burkina Faso.

OBJECTIVE: To underline peculiar composition of kidney stones and to propose an epidemiologic study of urinary stones in West African countries, where epidemiologic studies are scarce. Only few data are available regarding stone composition in sub-Saharan countries. Recently, a set of 100 stones consecutively removed by surgery in the Department of Urology of the University Hospital of Ouagadougou in Burkina Faso were collected for physical analysis, which provided the opportunity to obtain an epidemiologic profile of stone composition in this country. MATERIALS AND METHODS: A total of 100 stones from 64 men, 22 women, 10 boys, and four girls were analyzed by morphologic examination, infrared spectroscopy, and electron microscopy in our laboratory. The results were considered by sex and separately for adults and children. RESULTS: Sixty-five percent of the 100 stones contained calcium oxalate as the main component. Interestingly, the second main component was opaline silica (18%). Furthermore, opaline silica was identified in any proportion in 48% of the stones. The prevalence was sex and age dependent. Opaline silica was detected as the main component in 42% of the nuclei, which underlines its role as one of the main components involved in the initiation of calculi in this country. CONCLUSION: For the first time, a dramatically high occurrence of a "scarce" urinary stone component, namely opaline silica, was reported in a series of consecutive calculi from a single country. We propose that a regular consumption of clay could be the origin of this phenomenon in these populations.