title: The rapid manufacture of uniform composite multicellular-biomaterial micropellets, their assembly into macroscopic organized tissues, and potential applications in cartilage tissue engineering.
abstract: We and others have published on the rapid manufacture of micropellet tissues, typically formed from 100-500 cells each. The micropellet geometry enhances cellular biological properties, and in many cases the micropellets can subsequently be utilized as building blocks to assemble complex macrotissues. Generally, micropellets are formed from cells alone, however when replicating matrix-rich tissues such as cartilage it would be ideal if matrix or biomaterials supplements could be incorporated directly into the micropellet during the manufacturing process. Herein we describe a method to efficiently incorporate donor cartilage matrix into tissue engineered cartilage micropellets. We lyophilized bovine cartilage matrix, and then shattered it into microscopic pieces having average dimensions < 10 μm diameter; we termed this microscopic donor matrix "cartilage dust (CD)". Using a microwell platform, we show that ~0.83 μg CD can be rapidly and efficiently incorporated into single multicellular aggregates formed from 180 bone marrow mesenchymal stem/stromal cells (MSC) each. The microwell platform enabled the rapid manufacture of thousands of replica composite micropellets, with each micropellet having a material/CD core and a cellular surface. This micropellet organization enabled the rapid bulking up of the micropellet core matrix content, and left an adhesive cellular outer surface. This morphological organization enabled the ready assembly of the composite micropellets into macroscopic tissues. Generically, this is a versatile method that enables the rapid and uniform integration of biomaterials into multicellular micropellets that can then be used as tissue building blocks. In this study, the addition of CD resulted in an approximate 8-fold volume increase in the micropellets, with the donor matrix functioning to contribute to an increase in total cartilage matrix content. Composite micropellets were readily assembled into macroscopic cartilage tissues; the incorporation of CD enhanced tissue size and matrix content, but did not enhance chondrogenic gene expression.
authors.affiliation: Stem Cell Therapies Laboratory, Institute of Health and Biomedical Innovation, Queensland University of Technology at the Translational Research Institute, Brisbane, Australia.
authors.forename: Betul Kul
authors.initials: BK
authors.lastname: Babur
authors.affiliation: Stem Cell Therapies Laboratory, Institute of Health and Biomedical Innovation, Queensland University of Technology at the Translational Research Institute, Brisbane, Australia; Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran.
authors.forename: Mahboubeh
authors.initials: M
authors.lastname: Kabiri
authors.affiliation: Cartilage Regeneration Laboratory, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
authors.forename: Travis Jacob
authors.initials: TJ
authors.lastname: Klein
authors.affiliation: Stem Cell Therapies Laboratory, Institute of Health and Biomedical Innovation, Queensland University of Technology at the Translational Research Institute, Brisbane, Australia.
authors.forename: William B
authors.initials: WB
authors.lastname: Lott
authors.affiliation: Stem Cell Therapies Laboratory, Institute of Health and Biomedical Innovation, Queensland University of Technology at the Translational Research Institute, Brisbane, Australia; Mater Medical Research-University of Queensland, Brisbane, Australia.
authors.forename: Michael Robert
authors.initials: MR
authors.lastname: Doran
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000378:metabolism*; D002358:Cartilage, Articular / Q000166:cytology* / Q000254:growth & development; D002417:Cattle; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D020219:Chondrogenesis; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D010316:Particle Size; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D001672:Biocompatible Materials