15502-m-pleumeekers

and AMSCs was not significantly different, although a large donor variation was observed. Also with large variation between donors, AMSCs performed worse. The amount of collagen deposited was just above background for all cell sources after five weeks of chondrogenic differentiation, being on average 1.53 ± 1.84 μg collagen per alginate bead. (Figure 1C) Chondrogenic differentiation in vivo To study the stability and quality of TE cartilage in vivo , alginate constructs were first differentiated in vitro for five weeks and subsequently implanted subcutaneously on the dorsal side of athymic mice for an additional eight weeks of culture. Constructs seeded with ECs or NCs, pre-cultured with TGFβ1, had a macroscopically white opaque appearance and were relatively strong on handling. Conversely, constructs pre-cultured without TGFβ1 or constructs encapsulating ACs, BMSCs or AMSCs, were fragile and also did not resemble cartilaginous tissue macroscopically. (Figure 2A and 3A) Figure 2. Cartilage matrix formation by several cell types in vivo. Prior to subcutaneous implantation, constructs were cultured in vitro for 5 weeks in the absence of TGFβ1. (A) Macroscopic view of engineered cartilage constructs after 8 weeks of subcutaneous implantation. (B) Biochemical evaluation of the sGAG and collagen content after subcutaneous implantation. ECs and NCs deposited most sGAGs in vivo . Collagen-production was increased in vivo , but did not differ between the cell sources. The grey bars represent the in vivo biochemical data of constructs cultured in vitro for 5 weeks in the presence of TGFβ1 (Figure 3). (C) ECs and NCs demonstrated a collagen-type-II-rich matrix in almost all cartilage constructs. Biochemical data are shown as mean ± SD. For statistical evaluation, a mixed model was used. *, ** or *** indicates p -value smaller than 0.05, 0.01 or 0.001 respectively compared to the other cell sources. EC = Ear Chondrocytes ( n=3 donors) ; NC = Nasal Chondrocytes ( n=3 donors) ; AC = Articular Chondrocytes ( n=3 donors) ; BMSC = Bone-marrow-derived Mesenchymal Stem Cells ( n=3 donors) ; AMSC = Adipose-tissue-derived Mesenchymal Stem Cells ( n=3 donors). Per donor, 2 samples were used for analyses. 72 CHAPTER 4