Segmental Additive Tissue Engineering

Abstract

Segmental bone defects caused by trauma and disease represent a major clinical problem worldwide. Current treatment options are limited and often associated with poor outcomes and severe complications. Bone engineering is a promising alternative solution, but a number of technical challenges must be addressed to allow for effective and reproducible construction of segmental grafts that meet the size and geometrical requirements needed for individual patients and routine clinical applications. It is important to devise engineering strategies and standard operating procedures that make it possible to scale up the size of bone-engineered grafts, minimize process and product variability, and facilitate technology transfer and implementation. To address these issues, we have combined traditional and modular tissue engineering approaches in a strategy referred to as Segmental Additive Tissue Engineering (SATE). To demonstrate this approach, a digital reconstruction of a rabbit femoral defect was partitioned transversally to the longitudinal axis into segments (modules) with discoidal geometry and defined thickness to enable protocol standardization and effective tissue formation in vitro. Bone grafts corresponding to each segment were then engineered using biomimetic scaffolds seeded with human induced pluripotent stem cell-derived mesodermal progenitors (iPSC-MPs) and a novel perfusion bioreactor with universal design. The SATE strategy enables the effective and reproducible engineering of segmental bone grafts for personalized skeletal reconstruction, and will facilitate technology transfer and implementation of a tissue engineering approach to segmental bone defect therapy.

GMP-compatible and xeno-free cultivation of mesenchymal progenitors derived from human-induced pluripotent stem cells

“…This implies that large numbers of cells would need to be administered to achieve therapeutic efficacy. The same is true if MSCs are to be used to engineer tissue grafts for replacement therapies [17, 30, 31]. Unfortunately, human MSCs derived from adult tissues exhibit limited proliferation potential, and therapeutically, functional cells may not be available in sufficient numbers for every patient [3, 7, 11, 37, 40].…”

Hypothermic and cryogenic preservation of tissue‐engineered human bone

“…Human bone grafts ( n = 18) were engineered as previously described . Briefly, human iPSC‐derived mesenchymal progenitor cells (line 1013A) at passage 6 were plated onto gelatin‐coated plasticware and expanded in medium consisting of high‐glucose KnockOut Dulbecco's modified Eagle's medium (DMEM; Gibco) supplemented with 20% (v/v) HyClone™ fetal bovine serum (FBS; GE Healthcare Life Sciences), fibroblast growth factor basic (1 ng/mL; Invitrogen), nonessential amino acids (0.1 mM; Gibco), glutaMAX (2 mM; Gibco), beta‐mercaptoethanol (0.1 mM; Gibco), and antibiotic‐antimycotic (100 U/mL; Gibco).…”

“…Human iPSCs can be derived for every patient in virtually unlimited numbers, and represent a single cell source with the ability to differentiate into all of the specialized cells constituting the bone tissue . We recently engineered bone grafts by culturing human iPSC‐derived mesenchymal progenitors onto biomimetic scaffolds in bioreactors . In the present study, we asked whether these grafts could be preserved to allow distribution and banking, and studied the effects of two preservation methods on the tissue quality.…”

Mesenchymal Stromal Cell-Based Bone Regeneration Therapies: From Cell Transplantation and Tissue Engineering to Therapeutic Secretomes and Extracellular Vesicles

“…In order to scale-up and standardize these bone tissue engineering strategies to sizes relevant for preclinical studies in large animal models and for clinical applications (beyond reconstruction of smaller jaw bone defects), research has focused on advanced scaffold manufacturing technologies (recently reviewed in Forrestal et al, 2017) and on dynamic tissue culture in bioreactor systems (Meinel et al, 2004, 2005; Marolt et al, 2006; Timmins et al, 2007; Grayson et al, 2008, 2011; Fröhlich et al, 2010; Woloszyk et al, 2014). Perfusion systems that support the interstitial flow of culture medium through bone scaffolds showed the most promise for bone tissue engineering from MSCs originating from adult tissues and pluripotent stem cells (De Peppo et al, 2013; Vetsch et al, 2016; Mitra et al, 2017; Sladkova et al, 2018). The appropriate biochemical milieu and biophysical stimulation provided to the osteogenic cells by the fluid shear force on the cells allowed increased cell numbers and enhanced the uniform cell distribution and the amount of new bone matrix (Sikavitsas et al, 2003; Grayson et al, 2011; Zhao et al, 2018).…”