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• Schröder, Maria Elisabeth; Reseland, Janne Elin & Haugen, Håvard Jostein (2022). Osteoblasts in a Perfusion Flow Bioreactor—Tissue Engineered Constructs of TiO2 Scaffolds and Cells for Improved Clinical Performance. Cells. 11(13), p. 1995–1995. doi: 10.3390/cells11131995. Full text in Research Archive Show summary

  Combining biomaterial scaffolds with cells serves as a promising strategy for engineering critical size defects; however, homogenous cellular growth within large scaffolds is challenging. Mechanical stimuli can enhance bone regeneration by modulating cellular growth and differentiation. Here, we compare dynamic seeding in a perfusion flow bioreactor with static seeding for a synthetic bone scaffold for up to 21 days using the cell line MC3T3-E1 and primary human osteoblast, confocal laser scanning microscopy, and real-time reverse transcriptase-polymerase chain reaction. The secretion of bone-related proteins was quantified using multiplex immunoassays. Dynamic culture improved cellular distribution through the TiO2 scaffold and induced a five-fold increase in cell number after 21 days. The relative mRNA expression of osteopontin of MC3T3-E1 was 40-fold enhanced after 7 and 21 days at a flow rate of 0.08 mL/min, and that of collagen type I alpha I expression was 18-fold after 21 days. A flow rate of 0.16 mL/min was 10-fold less effective. Dynamic culture increased the levels of dickkopf-related protein 1 (60-fold), osteoprotegrin (29-fold), interleukin-6 (23-fold), interleukin-8 (36-fold), monocyte chemoattractant protein 1 (28-fold) and vascular endothelial growth factor (6-fold) in the medium of primary human osteoblasts after 21 days compared to static seeding. The proposed method may have clinical potential for bone tissue engineering.

• Yang, Yang; Pullisaar, Helen; Landin, Maria Augusta Dos S Silva; Heyward, Catherine Anne; Schröder, Maria & Geng, Tianxiang [Show all 8 contributors for this article] (2021). FNDC5/irisin is expressed and regulated differently in human periodontal ligament cells, dental pulp stem cells and osteoblasts. Archives of Oral Biology. ISSN 0003-9969. doi: 10.1016/j.archoralbio.2021.105061. Full text in Research Archive Show summary

  Objective To examine the expression and regulation of fibronectin type III domain-containing protein 5/irisin (FNDC5/irisin) in primary human periodontal ligament (hPDL) cells, dental pulp stem cells (hDPCs) and osteoblasts (hOBs). Methods FNDC5/irisin was identified in sections of paraffin embedded rat maxillae, cryo-sections of 3D cultured spheroids hPDL cells, hDPCs and hOBs, 2D cultured hPDL cells, hDPCs and hOBs by immunohistochemistry. The expression of FNDC5/irisin was identified by qPCR, followed by sequencing of the qPCR product. Regulation of FNDC5/irisin expression in hPDL cells, hDPCs and hOBs were evaluated after administration of different concentrations of irisin and all-trans retinoic acid (ATRA). qPCR and ELISA were used to identify expression and secretion of FNDC5/irisin in odontoblast-like differentiation of hDPCs. Results FNDC5/irisin was confirmed to be present in rat periodontium and dental pulp regions, as well as in 2D and 3D cultured hPDL cells, hDPCs and hOBs. BLAST analyses verified the generated nucleotide alignments matched human FNDC5/irisin. FNDC5/irisin gene expression was enhanced during odontoblast-like differentiation of hDPCs whereas the secretion of the protein was decreased compared to control. The protein signals in rat periodontal and pulpal tissues were higher than that of alveolar bone, and the expression of FNDC5/irisin was differently regulated by recombinant irisin and ATRA in hPDL cells and hDPCs compared to hOBs. Conclusions FNDC5/irisin expression was verified in rodent periodontium and dental pulp, and in hPDL cells, hDPCs and hOBs. The FNDC5/irisin expression was regulated by recombinant irisin and ATRA. Finally, expression and secretion of FNDC5/irisin were affected during odontoblast-like differentiation of hDPCs.

• Schröder, Maria; Riksen, Elisabeth Aurstad; He, Jianying; Skallerud, Bjørn Helge; Møller, Mona Elisabeth & Lian, Aina-Mari [Show all 8 contributors for this article] (2020). Vitamin K2 modulates vitamin D induced mechanical properties of human 3D bone spheroids in vitro. JBMR Plus. 4(9). doi: 10.1002/jbm4.10394. Full text in Research Archive Show summary

  Rotational culture promotes primary human osteoblasts (hOBs) to form three-dimensional (3D) multicellular spheroids with bone tissue-like structure without any scaffolding material. Cell-based bone models enable us to investigate the effect of different agents on the mechanical strength of bone. Given that low dietary intake of both vitamin D and K is negatively associated with fracture risk, we aimed to assess the effect of these vitamins in this system. Osteospheres of hOBs were generated with menaquinone-4 (MK-4; 10μM) and 25-hydroxyvitamin D3 [25(OH)D3; 0.01μM], alone and in combination, or without vitamins. The mechanical properties were tested by nanoindentation using a flat-punch compression method, and the mineralized extracellular bone matrix was characterized by microscopy. The in vitro response of hOBs to MK-4 and 25(OH)D3 was further evaluated in two-dimensional (2D) cultures and in the 3D bone constructs applying gene expression analysis and multiplex immunoassays. Mechanical testing revealed that 25(OH)D3 induced a stiffer and MK-4 a softer or more flexible osteosphere compared with control. Combined vitamin conditions induced the same flexibility as MK-4 alone. Enhanced levels of periostin (p < 0.001) and altered distribution of collagen type I (COL-1) were found in osteospheres supplemented with MK-4. In contrast, 25(OH)D3 reduced COL-1, both at the mRNA and protein levels, increased alkaline phosphatase, and stimulated mineral deposition in the osteospheres. With the two vitamins in combination, enhanced gene expression of periostin and COL-1 was seen, as well as extended osteoid formation into the central region and increased mineral deposition all over the area. Moreover, we observed enhanced levels of osteocalcin in 2D and osteopontin in 3D cultures exposed to 25(OH)D3 alone and combined with MK-4. In conclusion, the two vitamins seem to affect bone mechanical properties differently: vitamin D enhancing stiffness and K2 conveying flexibility to bone. These effects may translate to increased fracture resistance in vivo. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

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