Zhang Irene W, Choi Lucia S, Friend Nicole E, McCoy Atticus J, Midekssa Firaol S, Hu Michael M, Alsberg Eben, Lesher-Pérez Sasha Cai, Stegemann Jan P, Baker Brendon M, Putnam Andrew J
Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States.
Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, United States; Jesse Brown Veterans Affairs Medical Center (JBVAMC), Chicago, IL, United States.
Acta Biomater. 2025 Jul 1;201:283-296. doi: 10.1016/j.actbio.2025.06.006. Epub 2025 Jun 13.
The development of perfusable and multiscale vascular networks remains one of the largest challenges in tissue engineering. As such, there is a need for the creation of customizable and facile methods to produce robustly vascularized constructs. In this study, secondarily crosslinkable (clickable) poly(ethylene glycol)-norbornene (PEGNB) microbeads were produced and evaluated for their ability to sequentially support suspension bioprinting and microvascular self-assembly towards the aim of engineering hierarchical vasculature. The clickable PEGNB microbead slurry exhibited mechanical behavior suitable for suspension bioprinting of sacrificial bioinks, could be UV crosslinked into a granular construct post-print, and withstood evacuation of the bioink and subsequent perfusion of the patterned void space. Endothelial and stromal cells co-embedded within jammed RGD-modified PEGNB microbead slurries assembled into capillary-scale vasculature after secondary crosslinking of the beads into granular constructs, with endothelial tubules forming within the interstitial space between microbeads and supported by the perivascular association of the stromal cells. Microvascular self-assembly was not impacted by printing sacrificial bioinks into the cell-laden microbead support bath before UV crosslinking. Collectively, these results demonstrate that clickable PEGNB microbeads are a versatile substrate for both suspension printing and microvascular culture and may be the foundation for a promising methodology to engineer hierarchical vasculature. STATEMENT OF SIGNIFICANCE: In this study, we leveraged and combined advances in microgel biomaterials, granular hydrogels, suspension bioprinting, and vascular biology to create relatively large volume (>500 mm) vascularized constructs. We fabricated secondarily crosslinkable (clickable) poly(ethylene glycol)-norbornene (PEGNB) microbeads and demonstrated their ability to sequentially support suspension bioprinting and microvascular self-assembly towards the aim of engineering hierarchical vasculature. To the best of our knowledge, this is the first study that uses PEG microgels as supportive materials for bioprinting, and one of the first papers to document microvascular self-assembly within granular constructs. The combination of top-down and bottom-up approaches within a single construct represents a significant and innovative contribution that we believe will be of broad interest to the biomaterials and regenerative medicine communities.
可灌注多尺度血管网络的构建仍然是组织工程领域面临的最大挑战之一。因此，需要创建可定制且简便的方法来制造具有强大血管化功能的构建体。在本研究中，制备了可二次交联（可点击）的聚乙二醇 - 降冰片烯（PEGNB）微珠，并评估了其依次支持悬浮生物打印和微血管自组装的能力，以实现构建分层血管系统的目标。可点击的PEGNB微珠浆料表现出适合牺牲性生物墨水悬浮生物打印的机械性能，打印后可通过紫外线交联成颗粒状构建体，并能承受生物墨水的排空以及随后对图案化空隙空间的灌注。共嵌入拥挤的RGD修饰PEGNB微珠浆料中的内皮细胞和基质细胞在微珠交联成颗粒状构建体后组装成毛细血管尺度的血管系统，内皮小管在微珠之间的间隙空间内形成，并由基质细胞的血管周围关联提供支持。在紫外线交联之前将牺牲性生物墨水打印到载有细胞的微珠支撑浴中，并不影响微血管的自组装。总体而言，这些结果表明可点击的PEGNB微珠是用于悬浮打印和微血管培养的通用基质，可能是构建分层血管系统的一种有前景方法的基础。重要性声明：在本研究中，我们利用并结合了微凝胶生物材料、颗粒水凝胶、悬浮生物打印和血管生物学的进展，以创建相对大体积（>500立方毫米）的血管化构建体。我们制备了可二次交联（可点击）的聚乙二醇 - 降冰片烯（PEGNB）微珠，并展示了其依次支持悬浮生物打印和微血管自组装以构建分层血管系统的能力。据我们所知，这是第一项使用PEG微凝胶作为生物打印支撑材料的研究，也是最早记录颗粒状构建体内微血管自组装的论文之一。在单个构建体内将自上而下和自下而上的方法相结合，代表了一项重大的创新性贡献，我们相信这将引起生物材料和再生医学领域的广泛关注。
