High-throughput bone and cartilage micropellet manufacture, followed by assembly of micropellets into biphasic osteochondral tissue

• Published in: Cell and tissue research Vol. 361; no. 3; pp. 755 - 768
• Main Authors: Babur, Betul Kul, Futrega, Kathryn, Lott, William B, Klein, Travis Jacob, Cooper-White, Justin, Doran, Michael Robert
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-09-2015; Springer; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Biomedicine; Bone and Bones - cytology; Bones; Cartilage; Cartilage - cytology; Cell Culture Techniques; Cell Differentiation - physiology; Cells, Cultured; Cellular biology; Chondrocytes - cytology; Chondrogenesis - physiology; histology; Human Genetics; Humans; manufacturing; Mesenchymal Stromal Cells - cytology; Molecular Medicine; Osteogenesis - physiology; Proteomics; Regular; Regular Article; Stem cells; stromal cells; Tissue Engineering; Osteochondral defect repair; Human; Articular cartilage; Induction media; Tissue engineering; Micropellets; Mesenchymal stem/stromal cells
• ISSN: 0302-766X; 1432-0878
• DOI: 10.1007/s00441-015-2159-y

Engineered biphasic osteochondral tissues may have utility in cartilage defect repair. As bone-marrow-derived mesenchymal stem/stromal cells (MSC) have the capacity to make both bone-like and cartilage-like tissues, they are an ideal cell population for use in the manufacture of osteochondral tissues. Effective differentiation of MSC to bone-like and cartilage-like tissues requires two unique medium formulations and this presents a challenge both in achieving initial MSC differentiation and in maintaining tissue stability when the unified osteochondral tissue is subsequently cultured in a single medium formulation. In this proof-of-principle study, we used an in-house fabricated microwell platform to manufacture thousands of micropellets formed from 166 MSC each. We then characterized the development of bone-like and cartilage-like tissue formation in the micropellets maintained for 8–14 days in sequential combinations of osteogenic or chondrogenic induction medium. When bone-like or cartilage-like micropellets were induced for only 8 days, they displayed significant phenotypic changes when the osteogenic or chondrogenic induction medium, respectively, was swapped. Based on these data, we developed an extended 14-day protocol for the pre-culture of bone-like and cartilage-like micropellets in their respective induction medium. Unified osteochondral tissues were formed by layering 12,000 osteogenic micropellets and 12,000 chondrogenic micropellets into a biphasic structure and then further culture in chondrogenic induction medium. The assembled tissue was cultured for a further 8 days and characterized via histology. The micropellets had amalgamated into a continuous structure with distinctive bone-like and cartilage-like regions. This proof-of-concept study demonstrates the feasibility of micropellet assembly for the formation of osteochondral-like tissues for possible use in osteochondral defect repair.