Chondrogenic differentiation of bone marrow concentrate grown onto a hylauronan scaffold: rationale for its use in the treatment of cartilage lesions.

Bone marrow is one of the best characterized stem cell microenvironment that contains Mesenchymal Stem Cells (MSCs). MSCs have been indicated as a new option for regenerative medicine because of their ability to differentiate into bone, cartilage and adipose tissues. However, in vitro-cultivation of MSCs could be associated with some shortcomings such as the possibility of the de-differentiation or reprogramming of the cells and the increase of the risk of infection and contaminations. To overcome these problems, a new approach is represented by the use of Bone Marrow Concentrate (BMC). This enables the implant of a cell population surrounded by its microenvironment preventing all the complications related to the in vitro-culture. Moreover, the cells within the bone marrow niche are able to regulate stem cell behavior through direct physical contact and by secreting paracrine factors. The aim of this study was to investigate the phenotype of cells within BMC and their ability to differentiate into chondrogenic lineage once seeded onto a hyaluronan-based scaffold (Hyaff-11) already used in clinic. The chondrogenic potential of BMC has been evaluated by means of morphological, histological, immunohistochemical and molecular analyses. The data obtained with the current study demonstrated that cells within BMC grown onto HYAFF-11 are able to differentiate into chondrogenic sense by the expression and production of specific extracellular molecules. These findings support the use of BMC in clinic for the repair of cartilage lesions allowing its transplantation in a "One Step" procedure.