Abstract
Introduction
Osteocytes play a role as mechanosensory cells by sensing flow-induced mechanical stimuli applied on their cell processes. High-resolution imaging of osteocyte processes and the canalicular wall are necessary for the analysis of this mechanosensing mechanism. Focused ion beam-scanning electron microscopy (FIB-SEM) enabled the visualization of the structure at the nanometer scale with thousands of serial-section SEM images. We applied machine learning for the automatic semantic segmentation of osteocyte processes and canalicular wall and performed a morphometric analysis using three-dimensionally reconstructed images.
Materials and methods
Six-week-old-mice femur were used. Osteocyte processes and canaliculi were observed at a resolution of 2 nm/voxel in a 4 × 4 μm region with 2000 serial-section SEM images. Machine learning was used for automatic semantic segmentation of the osteocyte processes and canaliculi from serial-section SEM images. The results of semantic segmentation were evaluated using the dice similarity coefficient (DSC). The segmented data were reconstructed to create three-dimensional images and a morphological analysis was performed.
Results
The DSC was > 83%. Using the segmented data, a three-dimensional image of approximately 3.5 μm in length was reconstructed. The morphometric analysis revealed that the median osteocyte process diameter was 73.8 ± 18.0 nm, and the median pericellular fluid space around the osteocyte process was 40.0 ± 17.5 nm.
Conclusion
We used machine learning for the semantic segmentation of osteocyte processes and canalicular wall for the first time, and performed a morphological analysis using three-dimensionally reconstructed images.
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References
Fujii O, Tatsumi S, Ogata M, Arakaki T, Sakaguchi H, Nomura K, Miyagawa A, Ikuta K, Hanazaki A, Kaneko I, Segawa H, Miyamoto K (2017) Effect of osteocyte-ablation on inorganic phosphate metabolism: analysis of bone–kidney–gut axis. Front Endocrinol 8:359
Donna P, Tammy B, Dara W, Karen K, Yun Y, Matthew P, Bonewald LF (2019) Elevated glucose acts directly on osteocytes to increase sclerostin expression in diabetes. Sci Rep 9:17353
Schaffler MB, Cheung WY, Majeska R, Kennedy O (2014) Osteocytes: master orchestrators of bone. Calcif Tissue Int 94:5–24
Bonewald LF (2009) The amazing osteocyte. J Bone Miner Res 26:229–238
Adachi T, Aonuma Y, Tanaka M, Hojo M, Takano-Yamamoto T, Kamioka H (2009) Calcium response in single osteocytes to locally applied mechanical stimulus: differences in cell process and cell body. J Biomech 42:1989–1995
Burr DB, Milgrom C, Fyhrie D, Forwood M, Nyska M, Finestone A, Hoshaw S, Saiag E, Simkin A (1996) In vivo measurement of human tibial strains during vigorous activity. Bone 18:405–410
Knothe TML (2003) “Whither flows the fluid in bone?” An osteocyte’s perspective. J Biomech 36:1409–1424
Fritton SP, Weinbaum S (2009) Fluid and solute transport in bone: flow-induced mechanotransduction. Annu Rev Fluid Mech 41:347–374
Cowin SC, Moss-Salentijn L, Moss ML (1991) Candidates for the mechanosensory system in bone. J Biomech Eng 113:191–197
Kamioka H, Kameo Y, Imai Y, Bakker AD, Bacabac RG, Yamada N, Takaoka A, Yamashiro T, Adachi T, Klein-Nulend J (2012) Microscale fluid flow analysis in a human osteocyte canaliculus using a realistic high-resolution image-based three- dimensional model. Integr Biol 4:1198–1206
Hara T (2014) Recent improvement of a FIB-SEM serial-sectioning method for precise 3D image reconstruction-application of the orthogonally-arranged FIB-SEM. Microscopy 63:1
Hashimoto M, Nagaoka N, Tabata K, Tanaka T, Osumi R, Odagaki N, Hara T, Kamioka H (2017) Three-dimensional morphometry of collagen fibrils in membranous bone. Integr Biol 9:868–875
Hasegawa T, Yamamoto T, Hongo H, Qiu Z, Miki Abe M, Kanesaki T, Tanaka K, Endo T, Paulo HLF, Li M, Amizuka N (2018) Three-dimensional ultrastructure of osteocytes assessed by focused ion beam-scanning electron microscopy (FIB-SEM). Histochem Cell Biol 149:423–432
Tang F, Liang S, Zhong T, Huang X, Deng X, Zhang Y, Zhou L (2019) Postoperative glioma segmentation in CT image using deep feature fusion model guided by multi-sequence MRIs. Eur Radiol 30:823–832
Remedios S, Roy S, Blaber J, Bermudez C, Nath V, Patel MB, Butman JA, Landman BA, Pham DL (2019) Distributed deep learning for robust multi-site segmentation of CT imaging after traumatic brain injury. Proc SPIE Int Soc Opt Eng 10949:109490A
Savi FM, Brierly GI, Baldwin J, Theodoropoulos C, Woodruff MA (2017) Comparison of different decalcification methods using rat mandibles as a model. J Histochem Cytochem 65:705–722
Shapiro F, Cahill C, Malatantis G, Nayak RC (1995) Transmission electron microscopic demonstration of vimentin in rat osteoblast and osteocyte cell bodies and processes using the immunogold technique. Anat Rec 241:39–48
Sugawara Y, Kamioka H, Ishihara Y, Fujisawa N, Kawanabe N, Yamashiro T (2013) The early mouse 3D osteocyte network in the presence and absence of mechanical loading. Bone 52:189–196
Schneider P, Meier M, Wepf R, Müller R (2010) Towards quantitative 3D imaging of the osteocyte lacuno-canalicular network. Bone 47:848–858
Schindelin J, Arganda-Carreras I, Frise E, Kaynig V, Longair M, Pietzsch T, Preibisch S, Rueden C, Saalfeld S, Schmid B, Tinevez JY, White DJ, Hartenstein V, Eliceiri K, Tomancak P, Cardona A (2012) Fiji: an open-source platform for biological-image analysis. Nat Methods 28:676–682
Arganda-Carreras I, Kaynig V, Rueden C, Eliceiri KW, Schindelin J, Cardona A, Seung HS (2017) Trainable Weka segmentation: a machine learning tool for microscopy pixel classification. Bioinformatics 33:2424–2426
Welch W, Witkin A (2015) Free-form shape design using triangulated surfaces. Sensors 15:12782–12801
Tanaka-Kamioka K, Kamioka H, Ris H, Lim SS (1998) Osteocyte shape is dependent on actin filaments and osteocyte processes are unique actin-rich projections. J Bone Miner Res 13:1555–1568
Polan DF, Brady SL, Kaufman RA (2016) Tissue segmentation of computed tomography images using a Random Forest algorithm: a feasibility study. Phys Med Biol 61:6553–6569
Zhou LQ, Wang JY, Yu SY, Wu GG, Wei Q, Deng YB, Xl Wu, Cui XW, Dietrich CF (2019) Artificial intelligence in medical imaging of the liver. World J Gastroenterol 25:672–682
You L, Cowin SC, Schaffler MB, Weinbaum S (2001) A model for strain amplification in the actin cytoskeleton of osteocytes due to fluid drag on pericellular matrix. J Biomech 34:1375–1386
Han Y, Cowin SC, Mitchell B, Schaffler MB, Weinbaum S (2004) Mechanotransduction and strain amplification in osteocyte cell processes. Proc Natl Acad Sci USA 101:16689–16694
Anderson EJ, Melissa L, Knothe Tate ML (2008) Idealization of pericellular fluid space geometry and dimension results in a profound underprediction of nano-microscale stresses imparted by fluid drag on osteocytes. J Biomech 41:1736–1746
Yokoyama Y, Kameo Y, Kamioka H, Adachi T (2021) High-resolution image-based simulation reveals membrane strain concentration on osteocyte processes caused by tethering elements. Biomech Model Mechanobiol. https://doi.org/10.1007/s10237-021-01511-y
van Tol AF, Roschger A, Repp F, Chen J, Roschger P, Berzlanovich A, Gruber GM, Fratzl P, Weinkamer R (2020) Network architecture strongly influences the fluid flow pattern through the lacunocanalicular network in human osteons. Biomech Model Mechanobiol 19:823–840
van Tol AF, Schemenz V, Wagermaier W, Roschger A, Razi H, Vitienes I, Fratzl P, Willie BM, Weinkamer R (2020) The mechanoresponse of bone is closely related to the osteocyte lacunocanalicular network architecture. Proc Natl Acad Sci USA 117:32251–32259
Dallas SL, Prideaux M, Bonewald LF (2013) The osteocyte: an endocrine cell … and more. Endocr Rev 34:658–690
Chen H, Senda T, Kubo KY (2015) The osteocyte plays multiple roles in bone remodeling and mineral homeostasis. Med Mol Morphol 48:61–68
Acknowledgements
This study was supported by the NIMS microstructural characterization platform as a program of the Nanotechnology Platform of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (JPMXP09A20NM0039), and the Japan Society for the Promotion of Science in the form of Grants-in-Aid for Research (JP19H03859 and JP19K19295). The authors would like to thank Akiko Nakamura (NIMS), Yuka Hara (NIMS), and Itsuro Kamimura (Maxnet Co., Ltd) for their technical supports.
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HK, KT, MH and ZW designed the study. KT, MH, NN, and TH conducted the study. KT, MH, ZW and HT processed, analyzed, and visualized the data. KT, MH wrote the manuscript and prepared figures. KT, NN, TH, and HK interpreted the data and approved the final version of the manuscript. HK is responsible for the integrity of the data analysis.
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Tabata, K., Hashimoto, M., Takahashi, H. et al. A morphometric analysis of the osteocyte canaliculus using applied automatic semantic segmentation by machine learning. J Bone Miner Metab 40, 571–580 (2022). https://doi.org/10.1007/s00774-022-01321-x
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DOI: https://doi.org/10.1007/s00774-022-01321-x