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International

Journal of Bioprinting

RESEARCH ARTICLE
3D-bioprinted osteocytes expressing Wnt7b

protect osteoblast differentiation from
microgravity

Jinling Zhang 1† id , Pengtao Wang 1† id , Xiaoling Chen 1 id , Saima Khan 1 id ,
Haiping Ouyang 2 id , Yangxi Liu 2 id , Bo He , Xian Li 3 id , Xing Liu *,
2
2
and Xiaolin Tu *
1 id
1 Laboratory of Skeletal Development and Regeneration, Key Laboratory of Clinical Laboratory
Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University,
Chongqing, China
2 Department of Orthopedics, Ministry of Education Key Laboratory of Child Development and
Disorders, National Clinical Research Center for Child Health and Disorders, Children’s Hospital of
Chongqing Medical University, Chongqing, China
3 College of Medical Informatics, Chongqing Medical University, Chongqing, China

Abstract

Maintaining bone formation in microgravity/weightless environments remains a
major challenge. Under weightless conditions, osteocytes act as mechanosensors to
inhibit Wnt canonical signaling and bone formation by secreting sclerostin. This study
† These authors contributed equally explores whether osteocytic Wnt7b can counteract microgravity-induced bone loss
to this work. through Wnt non-canonical signaling. Unlike previous bioprinting studies that focused
on structural scaffolds or generic cell types, a novel bioprinted scaffold consisting of
*Corresponding authors:
Xiaolin Tu polycaprolactone (supportive) and osteocyte (functional) hydrogels was constructed
(xtu@cqmu.edu.cn) in this study. Osteocytes overexpressing Wnt7b were co-cultured with bone marrow
Xing Liu stromal cells (ST2) in a 3D biomimetic weightless biomicroenvironmental system
(400269@hospital.cqmu.edu.cn) (3D-BWBM) to assess osteogenic and lipogenic differentiation. The results indicated
Citation: Zhang J, Wang P, Chen that osteocytic Wnt7b enhanced osteogenic differentiation and mineralization of ST2
X, et al. 3D-bioprinted osteocytes cells via the Wnt non-canonical pathway PKCδ, while suppressing the expression of
expressing Wnt7b protect osteoblast
differentiation from microgravity. lipogenic markers (Pparg, Cebpa) and adipogenesis. Reverse transcription quantitative
Int J Bioprint. 2025;11(4):426-445. polymerase chain reaction (RT-qPCR) analysis revealed elevated expression of Sost
doi: 10.36922/IJB025240238 and Mef2c, downregulation of the Wnt target gene Opg, and elevated expression of
Received: June 12, 2025 pro-osteoclastogenic cytokine Rankl and pro-inflammatory cytokines Tnfa and Il1b,
Accepted: July 3, 2025 thus validating the microgravity effect. Unlike conventional 2D culture of RCCS™
Published Online: July 3, 2025 cells, the 3D hydrogels were printed with tunnels (500 μm) for efficient nutrient/
Copyright: © 2025 Author(s). metabolite exchange, resulting in good cell growth, high cell viability (97%), and a
This is an Open Access article six-fold increase in proliferative activity within 7 days. Wnt7b osteocytes were still
distributed under the terms of the
Creative Commons Attribution able to maintain the osteogenic differentiation of ST2 cells, as evidenced by elevated
License, permitting distribution alkaline phosphatase activity, mineralization (1.8-fold increase), and a decrease in
and reproduction in any medium, osteoblast marker genes (Alpl, Runx2, Col1a1). In conclusion, Wnt7b-PCKδ signaling
provided the original work is
properly cited. counteracts microgravity-induced bone loss, and further in vivo studies on osteocytic
Wnt7b are warranted to confirm this causal relationship.
Publisher’s Note: AccScience
Publishing remains neutral with
regard to jurisdictional claims in
published maps and institutional Keywords: 3D bioprinting; Microgravity; Osteogenic differentiation; Wnt7b; Wnt
affiliations. noncanonical signaling

Volume 11 Issue 4 (2025) 426 doi: 10.36922/IJB025240238