Rich forests, poor countries: adapting forest conservation to economic realities

In the Congo Basin, very large areas of species-rich forests exist in countries that are among the world's poorest. Decision makers and ordinary people in these countries are far more concerned about meeting short-term local and national needs than about long-term value of global biodiversity. Given present economic realities, it is hard to see how such investments can be sustained unless much greater emphasis is given to reconciling conservation objectives with economic needs. Forest conservation in the Congo Basin will require more diversified approahes in order to manage a wider range of land-use systems more effectively, at lower cost, and with significant more local and national participation. The current enthusiasm for the big, remote, pristine parks model of forest conservation is risky

Zonal Chondrocytes Seeded in a Layered Agarose Hydrogel Create Engineered Cartilage with Depth-Dependent Cellular and Mechanical Inhomogeneity

We hypothesized that zonal populations of chondrocytes seeded into a bilayered scaffold with initially prescribed depth-varying, compressive material properties will lead to a biomimetic cartilage tissue construct with depth-dependent cellular and compressive mechanical inhomogeneity similar to that of the native tissue. Superficial zone chondrocytes (SZCs) and middle/deep zone chondrocytes (MDZCs) were isolated and encapsulated with 2% or 3% agarose to form single-layered constructs of 2% SZC, 3% SZC, 2% MDZC; bilayered constructs of 2% SZC/2% MDZC and 3% SZC/2% MDZC; and 2% mixed chondrocyte controls. For SZCs on day 42, increased glycosaminoglycan (GAG) and collagen was found with increased agarose concentration and when layered with MDZCs. Superficial zone protein increased with agarose concentration in bilayered constructs. For MDZCs, increased GAG content and regulation of cell proliferation was observed when layered with SZCs. Bilayered constructs possessed a depth-dependent compressive modulus qualitatively similar to that of native articular cartilage, whereas controls showed a U-shaped profile with stiffer peripheral edges and softer middle region. This study is the first to create an engineered cartilage tissue with depth-varying cellular as well as mechanical inhomogeneity. Future studies will determine if replicating inhomogeneity is advantageous in clinical applications of tissue engineered cartilage