Bone tissue engineering bioreactors: a role in the clinic?
ABSTRACT Tissue engineered bone grafts have the potential to be used to treat large bone defects due to congenital abnormalities, cancer resections, or traumatic incidents. Recent studies have shown that perfusion bioreactors can be used to generate grafts of clinically relevant sizes and shapes. Despite these scientific and technological successes, there is uncertainty regarding the translational utility of bioreactor-based approaches due to the perceived high costs associated with these procedures. In fact, experiences over the past two decades have demonstrated that the widespread application of cell-based therapies is heavily dependent on the commercial viability. In this article, we directly address the question of whether bioreactors used to create bone grafts have the potential to be implemented in clinical approaches to bone repair and regeneration. We provide a brief review of tissue engineering approaches to bone repair, clinical trials that have employed cell-based methods, and advances in bioreactor technologies over the past two decades. These analyses are combined to provide a perspective on what is missing from the scientific literature that would enable an objective baseline for weighing the benefit of extended in vitro cultivation of cells into functional bone grafts against the cost of additional cultivation. In our estimation, the cost of bioreactor-based bone grafts may range from $10,000 to $15,000, placing it within the range of other widely used cell-based therapies. Therefore, in situations where a clear advantage can be established for engineered grafts comprising patient-specific, autologous cells, engineered bone grafts may be a clinically feasible option.
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ABSTRACT: Perfusion bioreactor plays important role in supporting 3D bone construct development. Scaffolds of chitosan composites have been studied to support bone tissue regeneration from osteogenic progenitor cells including human mesenchymal stem cells (hMSC). In this study, porous scaffolds of hydroxyapatite (H), chitosan (C), and gelatin (G) were fabricated by phase-separation and press-fitted in the perfusion bioreactor system where media flow is configured either parallel or transverse with respect to the scaffolds to investigate the impact of flow configuration on hMSC proliferation and osteogenic differentiation. The in vitro results showed that the interstitial flow in the transverse flow (TF) constructs reduced cell growth during the first week of culture but improved spatial cell distribution and early onset of osteogenic differentiation measured by alkaline phosphatase (ALP) and expression of osteogenic genes. After 14 days of bioreactor culture, the TF constructs have comparable cell number but higher expression of bone markers genes and proteins compared to the parallel flow (PF) constructs. To evaluate ectopic bone formation, the HCG constructs seeded with hMSCs pre-cultured under two flow configurations for 7 days were implanted in CD-1 nude mice. While Masson's Trichrom staining revealed bone formation in both constructs, the TF constructs have improved spatial cell and osteoid distribution throughout the 2.0 mm constructs. The results highlight the divergent effects of media flow over the course of construct development and suggest that the flow configuration is an important parameter regulating the cellular events leading to bone construct formation in the HCG scaffolds. This article is protected by copyright. All rights reserved.Journal of Biomedical Materials Research Part A 12/2014; DOI:10.1002/jbm.a.35386 · 2.83 Impact Factor
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ABSTRACT: The use of multifactorial design of experiments (DoE) in tissue engineering bioprocess development will contribute to the robust manufacturing of tissue engineered constructs by linking their quality characteristics to bioprocess operating parameters. In this work, perfusion bioreactors were used for the in vitro culture and osteogenic differentiation of human periosteum-derived cells (hPDCs) seeded on three-dimensional titanium (Ti) alloy scaffolds. A CaP-supplemented medium was used to induce differentiation of the cultured hPDCs. A two-level, three-factor fractional factorial design was employed to evaluate a range of bioreactor operating conditions by changing the levels of the following parameters: flow rate (0.5–2 mL/min), cell culture duration (7–21 days) and cell seeding density (1.5 × 10^3–3 × 10^3 cells/cm2). This approach allowed for evaluating the individual impact of the aforementioned process parameters upon a range of genes that are related to the osteogenic lineage, such as collagen type I, alkaline phosphatase, osterix, osteopontin and osteocalcin. Furthermore, by overlaying gene-specific response surfaces, an integrated operating process space was highlighted within which predetermined values of the six genes of interest (i.e., gene signature) could be minimally met over the course of the bioreactor culture time.08/2014; 2(3):639-657. DOI:10.3390/pr2030639
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ABSTRACT: The development of cell based Advanced Therapeutic Medicinal Products (ATMPs) for bone repair has been expected to revolutionize the health care system for the clinical treatment of bone defects. Despite this great promise, the clinical outcomes of the few cell based ATMPs that have been translated into clinical treatments have been far from impressive. In part, the clinical outcomes have been hampered because of the simplicity of the first wave of products. In response the field has set-out and amassed a plethora of complexities to alleviate the simplicity induced limitations. Many of these potential second wave products have remained “stuck” in the development pipeline. This is due to a number of reasons including the lack of a regulatory framework that has been evolving in the last years and the shortage of enabling technologies for industrial manufacturing to deal with these novel complexities. In this review, we reflect on the current ATMPs and give special attention to novel approaches that are able to provide complexity to ATMPs in a straightforward manner. Moreover, we discuss the potential tools able to produce or predict ‘Goldilocks’ ATMPs, which are neither too simple nor too complex.Advanced Drug Delivery Reviews 11/2014; DOI:10.1016/j.addr.2014.10.025 · 12.71 Impact Factor