Bioprinting of an osteocyte network for biomimetic mineralization

Abstract

Osteocytes, essential regulators of bone homeostasis, are embedded in the mineralized bone matrix. Given the spatial arrangement of osteocytes, bioprinting represents an ideal method to biofabricate a 3D osteocyte network with a suitable surrounding matrix similar to native bone tissue. Here, we reported a 3D bioprinted osteocyte-laden hydrogel for biomimetic mineralization in vitro with exceptional shape fidelity, a high cell density (107 cells per ml) and high cell viability (85%–90%). The bioinks were composed of biomimetic modified biopolymers, namely, gelatine methacrylamide (GelMA) and hyaluronic acid methacrylate (HAMA), with or without type I collagen. The osteocyte-laden constructs were printed and cultured in mineralization induction media. After 28 d, increased dendritic cell connections and enhanced mineralized matrix production were observed after the addition of type I collagen. These results were further confirmed by the expression of osteocyte-related genes, markers of osteocyte morphology (Connexin43 and E11/Podoplanin), markers of mineralization (dentin matrix acidic phosphoprotein 1 (Dmp1)) and the cellular response to parathyroid hormone (PTH). Moreover, the 3D bioprinting constructs outperformed the 2D monolayer culture and they were at least comparable to 3D casted hydrogels in mimicking the natural osteocyte phenotype. All results indicated that the 3D bioprinting osteocyte network shows promise for mechanistic studies and pharmaceutical screening in vitro.

A 3D-bioprinted scaffold with doxycycline-controlled BMP2-expressing cells for inducing bone regeneration and inhibiting bacterial infection

“…Ensuring cell survival was the primary function of the scaffold, whereas successful synthesis and secretion of BMP2 by cells was key to its osteo-inductive ability. In our previous study, we demonstrated that the bioink used in this study can maintain the viability and function of loaded cells for a long period of time [ 42 ]. The benefits of using this bioink were demonstrated again in this study.…”

3D Printing and Bioprinting to Model Bone Cancer: The Role of Materials and Nanoscale Cues in Directing Cell Behavior

“…The most used cells for 3D bone bioprinting in orthopedics are murine or human MSCs from either bone marrow or adipose tissue [87,110,113,[147][148][149][150][151], murine calvarial MC3T3-E1 pre-osteoblast cells [46,68,152], and human fetal osteoblasts [105,147,153]. Printing of osteocytes has also been recently proposed [154]. These cells, when cultured in osteoinductive media or in media added with growth factors (i.e., bone morphogenic protein-2 BMP-2 [76,132,[155][156][157][158], FGF-2 [112,159], VEGF [74,147]) and/or other additives (i.e., Ca ++ ) [102,107], express osteogenic markers (i.e., ALP, osteonectin (ON), osteopontin (OPN), osteocalcin (OCN)) and markers of late osteocyte phenotype (i.e., podoplanin (PDPN) and sclerostin (SOST)), and are able to mineralize.…”

“…On the other hand, they should reproduce ECMcells interactions, thereby allowing the study of the mechanisms occurring in osteolytic or osteoblastic lesions, both in primary and secondary bone tumors. Silk fibroin and chitosan [75,107,110,120,158,160,161], collagen [113,133,145,150,154] and hyaluronic acid [76,78,116,148,151], chemically modified (i.e., methacrylation reaction) or used in blends [98,105,116,161] are among the most widely natural hydrogels employed to induce bone formation. These polymers have biological and chemical features resembling the organic ECM components of bone native tissue.…”

Nanotechnologies and Nanomaterials in 3D (Bio)printing toward Bone Regeneration

“…In addition, an extrusion‐based 3D‐bioprinted osteocyte‐laden hydrogel structurally similar to the native bone tissue was fabricated achieving good shape fidelity and 10 7 mL −1 of cell density. [ 88 ] Cell connections and production of a mineralized matrix was enhanced by the 3D‐bioprinted osteocyte‐laden GelMA and hyaluronic acid methacrylate (HAMA) constructs when Col‐I was presented mimicking the natural osteocyte phenotype. The addition of Col‐I could improve the physical behavior of the 3D HAMA/GelMA/Col‐I construct and promote osteocyte‐related gene expressions as well as biomimetic mineralization.…”