Animal models for bone tissue engineering and modelling disease

Tissue engineering and its clinical application, regenerative medicine, are instructing multiple approaches to aid in replacing bone loss after defects caused by trauma or cancer. In such cases, bone formation can be guided by engineered biodegradable and nonbiodegradable scaffolds with clearly defined architectural and mechanical properties informed by evidence-based research. With the ever-increasing expansion of bone tissue engineering and the pioneering research conducted to date, preclinical models are becoming a necessity to allow the engineered products to be translated to the clinic. In addition to creating smart bone scaffolds to mitigate bone loss, the field of tissue engineering and regenerative medicine is exploring methods to treat primary and secondary bone malignancies by creating models that mimic the clinical disease manifestation. This Review gives an overview of the preclinical testing in animal models used to evaluate bone regeneration concepts. Immunosuppressed rodent models have shown to be successful in mimicking bone malignancy via the implantation of human-derived cancer cells, whereas large animal models, including pigs, sheep and goats, are being used to provide an insight into bone formation and the effectiveness of scaffolds in induced tibial or femoral defects, providing clinically relevant similarity to human cases. Despite the recent progress, the successful translation of bone regeneration concepts from the bench to the bedside is rooted in the efforts of different research groups to standardise and validate the preclinical models for bone tissue engineering approaches

A Method for Prostate and Breast Cancer Cell Spheroid Cultures Using Gelatin Methacryloyl-Based Hydrogels.

Modern tissue engineering technologies have delivered tools to recreate a cell's naturally occurring niche in vitro and to investigate normal and pathological cell-cell and cell-niche interactions. Hydrogel biomaterials mimic crucial properties of native extracellular matrices, including mechanical support, cell adhesion sites and proteolytic degradability. As such, they are applied as 3D cell culture platforms to replicate tissue-like architectures observed in vivo, allowing physiologically relevant cell behaviors. Here we review bioengineered 3D approaches used for prostate and breast cancer. Furthermore, we describe the synthesis and use of gelatin methacryloyl-based hydrogels as in vitro 3D cancer model. This platform is used to engineer the microenvironments for prostate and breast cancer cells to study processes regulating spheroid formation, cell functions and responses to therapeutic compounds. Collectively, these bioengineered 3D approaches provide cell biologists with innovative pre-clinical tools that integrate the complexity of the disease seen in patients to advance our knowledge of cancer cell physiology and the contribution of a tumor's surrounding milieu

The effect of beta-tricalcium phosphate on mechanical and thermal performances of poly(lactic acid)

Orthophosphates are bioactive crystals with similar structure, in terms of elemental composition and crystal nature, to human bone. In this work, biocomposite materials were prepared with poly(lactic acid) (PLA) as matrix, and betatricalcium phosphate (b-TCP) as osteoconductive filler by extrusion-compounding followed by conventional injection molding. The b-TCP load content was varied in the 10 40 wt% range and the influence of the b-TCP load on mechanical performance of PLA/b-TCP composites was evaluated. Mechanical properties of composites were obtained by standardized tensile, flexural, impact, and hardness tests. Thermal analysis of composites was carried out by means of differential scanning calorimetry; degradation at high temperatures was studied by thermogravimetric analysis; and the effect of the b-TCP load on dynamical response of composites was studied by mechanical thermal analysis in torsion mode. The bestbalanced properties were obtained for PLA composites containing 30 wt% b-TCP with a remarkable increase in the Young s modulus. These materials offer interesting properties to be used as base materials for medical applications such as interference screws due to high stiffness and mechanical resistance.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by "Conselleria d'Educacio, Cultura i Esport" - Generalitat Valenciana ref: GV/2014/008.Ferri Azor, JM.; Gisbert, I.; García Sanoguera, D.; Reig Pérez, MJ.; Balart Gimeno, RA. (2016). The effect of beta-tricalcium phosphate on mechanical and thermal performances of poly(lactic acid). Journal of Composite Materials. 50(30):4189-4198. https://doi.org/10.1177/0021998316636205S41894198503

Tie-2 regulates the stemness and metastatic properties of prostate cancer cells.

Ample evidence supports that prostate tumor metastasis originates from a rare population of cancer cells, known as cancer stem cells (CSCs). Unfortunately, little is known about the identity of these cells, making it difficult to target the metastatic prostate tumor. Here, for the first time, we report the identification of a rare population of prostate cancer cells that express the Tie-2 protein. We found that this Tie-2High population exists mainly in prostate cancer cell lines that are capable of metastasizing to the bone. These cells not only express a higher level of CSC markers but also demonstrate enhanced resistance to the chemotherapeutic drug Cabazitaxel. In addition, knockdown of the expression of the Tie-2 ligand angiopoietin (Ang-1) led to suppression of CSC markers, suggesting that the Ang-1/Tie-2 signaling pathway functions as an autocrine loop for the maintenance of prostate CSCs. More importantly, we found that Tie-2High prostate cancer cells are more adhesive than the Tie-2Low population to both osteoblasts and endothelial cells. Moreover, only the Tie-2High, but not the Tie-2Low cells developed tumor metastasis in vivo when injected at a low number. Taken together, our data suggest that Tie-2 may play an important role during the development of prostate tumor metastasis.published_or_final_versio

A humanised tissue-engineered bone model allows species-specific breast cancer-related bone metastasis in vivo.

Bone metastases frequently occur in the advanced stages of breast cancer. At this stage, the disease is deemed incurable. To date, the mechanisms of breast cancer-related metastasis to bone are poorly understood. This may be attributed to the lack of appropriate animal models to investigate the complex cancer cell-bone interactions. In this study, two established tissue-engineered bone constructs (TEBCs) were applied to a breast cancer-related metastasis model. A cylindrical medical-grade polycaprolactone-tricalcium phosphate scaffold produced by fused deposition modelling (scaffold 1) was compared with a tubular calcium phosphate-coated polycaprolactone scaffold fabricated by solution electrospinning (scaffold 2) for their potential to generate ectopic humanised bone in NOD/SCID mice. While scaffold 1 was found not suitable to generate a sufficient amount of ectopic bone tissue due to poor ectopic integration, scaffold 2 showed excellent integration into the host tissue, leading to bone formation. To mimic breast cancer cell colonisation to the bone, MDA-MB-231, SUM1315, and MDA-MB-231BO breast cancer cells were cultured in polyethylene glycol-based hydrogels and implanted adjacent to the TEBCs. Histological analysis indicated that the breast cancer cells induced an osteoclastic reaction in the TEBCs, demonstrating analogies to breast cancer-related bone metastasis seen in patients.Queensland University of Technology, the Australian Research Council (ARC) and the German Academic Exchange Service (DAAD

Lycopene reduces ovarian tumor growth and intraperitoneal metastatic load

Mutagens like oxidants cause lesions in the DNA of ovarian and fallopian tube epithelial cells, resulting in neoplastic transformation. Reduced exposure of surface epithelia to oxidative stress may prevent the onset or reduce the growth of ovarian cancer. Lycopene is well-known for its excellent antioxidant properties. In this study, the potential of lycopene in the prevention and treatment of ovarian cancer was investigated using an intraperitoneal animal model. Lycopene prevention significantly reduced the metastatic load of ovarian cancer-bearing mice, whereas treatment of already established ovarian tumors with lycopene significantly diminished the tumor burden. Lycopene treatment synergistically enhanced anti-tumorigenic effects of paclitaxel and carboplatin. Immunostaining of tumor and metastatic tissues for Ki67 revealed that lycopene reduced the number of proliferating cancer cells. Lycopene decreased the expression of the ovarian cancer biomarker, CA125. The anti-metastatic and anti-proliferative effects were accompanied by down-regulated expression of ITGA5, ITGB1, MMP9, FAK, ILK and EMT markers, decreased protein expression of integrin α5 and reduced activation of MAPK. These findings indicate that lycopene interferes with mechanisms involved in the development and progression of ovarian cancer and that its preventive and therapeutic use, combined with chemotherapeutics, reduces the tumor and metastatic burden of ovarian cancer in vivo

Ultra-porous titanium oxide scaffold with high compressive strength

Highly porous and well interconnected titanium dioxide (TiO2) scaffolds with compressive strength above 2.5 MPa were fabricated without compromising the desired pore architectural characteristics, such as high porosity, appropriate pore size, surface-to-volume ratio, and interconnectivity. Processing parameters and pore architectural characteristics were investigated in order to identify the key processing steps and morphological properties that contributed to the enhanced strength of the scaffolds. Cleaning of the TiO2 raw powder removed phosphates but introduced sodium into the powder, which was suggested to decrease the slurry stability. Strong correlation was found between compressive strength and both replication times and solid content in the ceramic slurry. Increase in the solid content resulted in more favourable sponge loading, which was achieved due to the more suitable rheological properties of the ceramic slurry. Repeated replication process induced only negligible changes in the pore architectural parameters indicating a reduced flaw size in the scaffold struts. The fabricated TiO2 scaffolds show great promise as load-bearing bone scaffolds for applications where moderate mechanical support is required

Humanization of the Prostate Microenvironment Reduces Homing of PC3 Prostate Cancer Cells to Human Tissue-Engineered Bone.

The primary tumor microenvironment is inherently important in prostate cancer (PCa) initiation, growth and metastasis. However, most current PCa animal models are based on the injection of cancer cells into the blood circulation and bypass the first steps of the metastatic cascade, hence failing to investigate the influence of the primary tumor microenvironment on PCa metastasis. Here, we investigated the spontaneous metastasis of PC3 human PCa cells from humanized prostate tissue, containing cancer-associated fibroblasts (CAFs) and prostate lymphatic and blood vessel endothelial cells (BVEC), to humanized tissue-engineered bone constructs (hTEBC) in NOD-SCID IL2Rγnull (NSG) mice. The hTEBC formed a physiologically mature organ bone which allowed homing of metastatic PCa cells. Humanization of prostate tissue had no significant effect on the tumor burden at the primary site over the 4 weeks following intraprostatic injection, yet reduced the incidence and burden of metastases in the hTEBC. Spontaneous PCa metastases were detected in the lungs and spleen with no significant differences between the humanized and non-humanized prostate groups. A significantly greater metastatic tumor burden was observed in the liver when metastasis occurred from the humanized prostate. Together, our data suggests that the presence of human-derived CAFs and BVECs in the primary PCa microenvironment influences selectively the metastatic and homing behavior of PC3 cells in this model. Our orthotopic and humanized prostate cancer model developed via convergence of cancer research and tissue engineering concepts provides an important platform to study species-specific PCa bone metastasis and to develop and test therapeutic strategies.National Health and Medical Research Council (Project Grant 1082313 awarded to B.M.H. and D.W.H.), a Worldwide Cancer Research (Project Grant WWCR 15-11563 awarded to D.W.H.), Movember Foundation and the Prostate Cancer Foundation of Australia (Movember Revolutionary Team Award to D.W.H., E.D.W., and J.A.C.) and funding from the Australian Government Department of Health, Queensland Government (APCRC-Q)

Personalized scaffolding technologies for alveolar bone regenerative medicine

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149271/1/ocr12275.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149271/2/ocr12275_am.pd

Order versus Disorder: in vivo bone formation within osteoconductive scaffolds

In modern biomaterial design the generation of an environment mimicking some of the extracellular matrix features is envisaged to support molecular cross-talk between cells and scaffolds during tissue formation/remodeling. In bone substitutes chemical biomimesis has been particularly exploited; conversely, the relevance of pre-determined scaffold architecture for regenerated bone outputs is still unclear. Thus we aimed to demonstrate that a different organization of collagen fibers within newly formed bone under unloading conditions can be generated by differently architectured scaffolds. An ordered and confined geometry of hydroxyapatite foams concentrated collagen fibers within the pores, and triggered their self-assembly in a cholesteric-banded pattern, resulting in compact lamellar bone. Conversely, when progenitor cells were loaded onto nanofibrous collagen-based sponges, new collagen fibers were distributed in a nematic phase, resulting mostly in woven isotropic bone. Thus specific biomaterial design relevantly contributes to properly drive collagen fibers assembly to target bone regeneration