Endothelialized microrods for minimally invasive in situ neovascularization

Abstract

Despite the significant advancements in fabricating various scaffolding systems over the past decades, generation of functional tissues towards vascularization remains challenging for the currently available biofabrication approaches. On the other hand, the applicability of traditional surgical transplantation of vascularized tissue constructs is sometimes limited due to the sophisticated surgical procedures, which are invasive, leading to increased risks of scar formation and infection. Considering these facts, we present an innovative platform, the angiogenic microrods composed of sodium alginate/gelatin harboring proliferating endothelial cells using a specially designed double T-junction microfluidic device with an expansion chamber, for achieving minimally invasive neovascularization in situ. Such vessel-like microarchitectures could be derived through controlled penetration of the crosslinker genepin for the gelatin phase, ensuing differential degrees in crosslinking of peripheral and central portions of the microstructures, thus resulting in the formation of vascular lumen-like hollow cavities via endothelial cell migration and proliferation during culture in vitro. Furthermore, in vivo performance of the microrods was explored. We believe that the development of these modular microrods for minimally invasive delivery is of great interest and offers a convenient approach for vascularization in situ.

Modeling Endothelialized Hepatic Tumor Microtissues for Drug Screening

“…The cytotoxicity of PLGA PMs was analyzed using the CCK‐8 kit. [ 33 ] Briefly, HepG2 cells were seeded in a 96‐well plate at a density of 5 × 10 3 cells per well. Then, the cells were incubated with the leach solution of the PLGA PMs at different concentrations (0.25, 0.5, 1.0, and 1.5 mg mL −1 ) for 24, 48, and 72 h. DMEM containing phenol (0.64%, v/v) and pure DMEM were used as the positive and negative controls, respectively.…”

Advances in hydrogel-based vascularized tissues for tissue repair and drug screening

“…In this case, the hollow architectures of the scaffolds can be obtained firstly, and then the ECs are layout surrounded by the scaffold to mimic the blood vessel layer [ 1 , 45 , 76 ]. In another case, the cells can be initially distributed into the pre-solution of scaffold materials and then directly fixed in the perfusable architectures after shaping [ 45 , 50 , 62 , 77 , 78 ]. Despite the difference in the construction of blood vessels in vitro , the fabricated scaffolds in both instances can be utilized in transplanting, engineering functional tissues, and understanding correlates vascular disease [ 7 , 63 , 79 ].…”

“… Hydrogel composition Cell sources Shaping mechanism Advantages of shaping mechanism for vascularization Significant hydrogel properties Advantages for vasculature Refs. GelMA, gelatin HUVECs Thermal crosslinking and photocrosslinking Smooth gel filament extrusion at sol-gel transition and rapid UV gelation for structural support Natural sol-gel transition of the hydrogel systems; biocompatibility; porous structure Formation of the interconnected tubular channels within well-defined 3D architectures; a confluent endothelial layer in the inner surface of the channels; i n situ endothelialization of the channels [ 75 ] Alginate, gelatin HUVECs Ionic crosslinking and genepin penetration Rapidly fixation of microrods architectures and inducing HUVECs migration Rapidly crosslinking of alginate and controllable fixation of gelatin Unique fabrication of HUVECs-laden microrods and regulation of HUVECs migration within hydrogel microrods; formation of new capillaries and organization of intensive vascular networks in mice after injection for 21 d [ 78 ] GelMA, HGSM mBMSCs Photocrosslinking and covalently crosslinking Enhanced mechanical properties showing self-healing capability Synthetization of host-guest supramolecular hydrogel (HGGelMA) with high compressive strength and an excellent stretching ability; about 400% water content; 5.25-fold compression modulus of the HGGelMA (0.63 MPa) than that of pure GelMA (0.11 MPa) Higher expression level of blood vessel-related genes (SMA, CD31, and PDGF) in vivo than that of pure GelMA [ 87 ] GelMA, PEO HUVECs, HepG2, and NIH/3T3 cells Photocrosslinking and leaching The hierarchical porous structures enhancing proliferation of HUVECs Increased Yong's modulus of the GelMA-PEO with the increase of PEO concentration 3- and 4-fold proliferation of HUVECs in the hierarchical porous GelMA than that of standard GelMA on 3 d and 7 d, respectively [ 86 ] GelMA, gelatin …”

“…In this vein, a wide variety of ECs subtypes are currently available, ranging from primary isolated ECs to cells differentiated from progenitor or stem cell populations. Among others, HUVECs remain the most prevalent choice due to the relatively easy accessibility and alleviation of immune rejection [ 78 , 126 , 139 ]. Notably, HUVECs specifically express vascular endothelial cadherin (VE-Cad) and CD31, which is helpful in effectively identify them as ECs [ 78 , 107 , 130 ].…”

Construction of 3D-tumor model for drug screening:Application of microfluidics

“…结果显示免疫浸润 成分在肿瘤的每个阶段都发生变化, 表明免疫细胞对肿瘤发展有重要影响. TMEs 中的免疫细胞能够 增强恶性肿瘤细胞的增殖、 迁移和转移 [18~20] , ECs 是血管的主要细胞成分, 在 TMEs 中可被肿瘤细胞诱 导生成新血管, 也参与恶性肿瘤细胞转移 [21,22] . 肿瘤-Ecs 的相互作用对于微环境生理或病理影响较大， 如血管生成、 癌症转移和定植等, 肿瘤细胞和 ECs 之间的作用可通过旁分泌/并置作用影响肿瘤生长和 进展, 并诱导癌症治疗过程中的耐药性.…”