In this study, two types of prostate cancer cell lines, highly metastatic PC‐3 and low metastatic MDA PCa 2b (PCa) were cultured on bone mimetic scaffolds to recapitulate metastasis to bone. A unique in vitro 3D tumor model that uses a sequential culture (SC) of human mesenchymal stem cells followed by seeding with cancer cells after bone formation was initiated to study the phenotype‐specific interaction between prostate cancer cells and bone microenvironment. The PCa cells were observed to be less prolific and less metastatic, and to form multicellular tumoroids in the bone microenvironment, whereas PC‐3 cells were more prolific and were highly metastatic, and did not form multicellular tumoroids in the bone microenvironment. The metastatic process exhibited by these two prostate cancer cell lines showed a significant and different effect on bone mineralization and extracellular matrix formation. Excessive bone formation in the presence of PC‐3 and significant osteolysis in the presence of PCa were observed, which was also indicated by osteocalcin and MMP‐9 expression as measured by ELISA and qRT‐PCR. The field emission scanning electron microscopy images revealed that the structure of mineralized collagen in the presence of PC‐3 is different than the one observed in healthy bone. All experimental results indicated that both osteolytic and osteoblastic bone lesions can be recapitulated in our tumor testbed model and that different cancer phenotypes have a very different influence on bone at metastasis. The 3D in vitro model presented in this study provides an improved, reproducible, and controllable system that is a useful tool to elucidate osteotropism of prostate cancer cells. © 2019 The Authors.
Biomimetically mineralized collagen scaffolds are promising for bone regeneration, but vascularization of these materials remains to be addressed. Here, we engineered mineralized scaffolds using an osteopontin‐guided polymer‐induced liquid‐precursor mineralization method to recapitulate bone's mineralized nanostructure. SEM images of mineralized samples confirmed the presence of collagen with intrafibrillar mineral, also EDS spectra and FTIR showed high peaks of calcium and phosphate, with a similar mineral/matrix ratio to native bone. Mineralization increased collagen compressive modulus up to 15‐fold. To evaluate vasculature formation and pericyte‐like differentiation, HUVECs and hMSCs were seeded in a 4:1 ratio in the scaffolds for 7 days. Moreover, we used RT‐PCR to investigate the gene expression of pericyte markers ACTA2, desmin, CD13, NG2, and PDGFRβ. Confocal images showed that both nonmineralized and mineralized scaffolds enabled endothelial capillary network formation. However, vessels in the nonmineralized samples had longer vessel length, a larger number of junctions, and a higher presence of αSMA+mural cells. RT‐PCR analysis confirmed the downregulation of pericytic markers in mineralized samples. In conclusion, although both scaffolds enabled endothelial capillary network formation, mineralized scaffolds presented less pericyte‐supported vessels. These observations suggest that specific scaffold characteristics may be required for efficient scaffold vascularization in future bone tissue engineering strategies. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1522–1532, 2019.
more » « less- NSF-PAR ID:
- 10076433
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Biomedical Materials Research Part B: Applied Biomaterials
- Volume:
- 107
- Issue:
- 5
- ISSN:
- 1552-4973
- Page Range / eLocation ID:
- p. 1522-1532
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research. -
null (Ed.)Background Volumetric tissue-engineered constructs are limited in development due to the dependence on well-formed vascular networks. Scaffold pore size and the mechanical properties of the matrix dictates cell attachment, proliferation and successive tissue morphogenesis. We hypothesize scaffold pore architecture also controls stromal-vessel interactions during morphogenesis. Methods The interaction between mesenchymal stem cells (MSCs) seeded on hydroxyapatite scaffolds of 450, 340, and 250 μm pores and microvascular fragments (MVFs) seeded within 20 mg/mL fibrin hydrogels that were cast into the cell-seeded scaffolds, was assessed in vitro over 21 days and compared to the fibrin hydrogels without scaffold but containing both MSCs and MVFs. mRNA sequencing was performed across all groups and a computational mechanics model was developed to validate architecture effects on predicting vascularization driven by stiffer matrix behavior at scaffold surfaces compared to the pore interior. Results Lectin staining of decalcified scaffolds showed continued vessel growth, branching and network formation at 14 days. The fibrin gel provides no resistance to spread-out capillary networks formation, with greater vessel loops within the 450 μm pores and vessels bridging across 250 μm pores. Vessel growth in the scaffolds was observed to be stimulated by hypoxia and successive angiogenic signaling. Fibrin gels showed linear fold increase in VEGF expression and no change in BMP2. Within scaffolds, there was multiple fold increase in VEGF between days 7 and 14 and early multiple fold increases in BMP2 between days 3 and 7, relative to fibrin. There was evidence of yap/taz based hippo signaling and mechanotransduction in the scaffold groups. The vessel growth models determined by computational modeling matched the trends observed experimentally. Conclusion The differing nature of hypoxia signaling between scaffold systems and mechano-transduction sensing matrix mechanics were primarily responsible for differences in osteogenic cell and microvessel growth. The computational model implicated scaffold architecture in dictating branching morphology and strain in the hydrogel within pores in dictating vessel lengths.more » « less
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