Tessuto cartilagineo ingegnerizzato usando bioreattore dinamico a condizioni di ossigeno definite.

Mesenchymal stem cells maintained in appropriate culture conditions are capable of producing robust cartilage tissue. However, gradients in nutrient availability that arise during three-dimensional culture can result in the development of spatially inhomogeneous cartilage tissues with core regions devoid of matrix. Previous attempts at developing dynamic culture systems to overcome these limitations have reported suppression of mesenchymal stem cell chondrogenesis compared to static conditions. We hypothesize that by modulating oxygen availability during bioreactor culture, it is possible to engineer cartilage tissues of scale. The objective of this study was to determine whether dynamic bioreactor culture, at defined oxygen conditions, could facilitate the development of large, spatially homogeneous cartilage tissues using mesenchymal stem cell laden hydrogels. A dynamic culture regime was directly compared to static conditions for its capacity to support chondrogenesis of mesenchymal stem cells in both small and large alginate hydrogels. The influence of external oxygen tension on the response to the dynamic culture conditions was explored by performing the experiment at 20% O2 and 3% O2. At 20% O2, dynamic culture significantly suppressed chondrogenesis in engineered tissues of all sizes. In contrast, at 3% O2 dynamic culture significantly enhanced the distribution and amount of cartilage matrix components (sulphated glycosaminoglycan and collagen II) in larger constructs compared to static conditions. Taken together, these results demonstrate that dynamic culture regimes that provide adequate nutrient availability and a low oxygen environment can be employed to engineer large homogeneous cartilage tissues. Such culture systems could facilitate the scaling up of cartilage tissue engineering strategies towards clinically relevant dimensions.

L’obiettivo è quello di determinare se le condizioni presenti in un bioreattore dinamico a determinate concentrazioni di ossigeno possono facilitare lo sviluppo di vasti e omogenei tessuti cartilaginei utilizzando cellule staminali mesenchimali su idrogel. L’influenza dell’ossigeno su di un bio-reattore dinamico è stata studiata svolgendo esperimenti a 3% pO2 e al 20% pO2. Con una concentrazione di 20% pO2 una coltura dinamica sopprime la condrogenesi in tessuti ingegnerizzati di ogni grandezza, invece con 3% pO2 in coltura dinamica incrementa notevolmente la distribuzione e la quantità delle componenti della matrice cartilaginea in ampi tessuti rispetto a condizioni statiche. Presi insieme questi risultati dimostrano che una coltura dinamica permette un’adeguata disponibilità di nutrienti, mentre una bassa concentrazione di ossigeno ambientale può essere utilizzata per ingegnerizzare grandi tessuti cartilaginei.