Department of Sports Medicine, Peking University Third Hospital. Institute of Sports Medicine of Peking University. Beijing Key Laboratory of Sports Injuries. Beijing 100191, People's Republic of China.
Department of Sports Medicine, Peking University Third Hospital. Institute of Sports Medicine of Peking University. Beijing Key Laboratory of Sports Injuries. Beijing 100191, People's Republic of China..
Acta Biomater. 2021 Sep 1;131:262-275. doi: 10.1016/j.actbio.2021.06.026. Epub 2021 Jun 23.
Decellularized extracellular matrix (dECM) hydrogels are being increasingly investigated for use in bio-inks for three-dimensional cell printing given their good cytocompatibility and biomimetic properties. The osmotic pressure and stiffness of bio-ink are important factors affecting the biological functions of printed cells. However, little attention has been given to the osmotic pressure and stiffness of the dECM bio-inks. Here, we compared three types of commonly used acidic solutions in the bio-fabrication of a tendon derived dECM bio-ink for 3D cell printing (0.5 M acetic acid, 0.1 M hydrochloric acid and 0.02 M hydrochloric acid). We found that low pH value of 0.1 M hydrochloric acid could accelerate the digestion process for dECM powders. This could lead to a much softer dECM hydrogel with storage modulus less than 100 Pa. This soft dECM hydrogel facilitated the spreading and proliferation of stem cells encapsulated within it. It also showed better tendon-inducing ability compared with two others much stiffer dECM hydrogels. However, this over-digested dECM hydrogel was more unstable as it could shrink with the culture time going on. For 0.5 M acetic acid made dECM bio-ink, the hyperosmotic state of the bio-ink led to much lower cellular viability rates. Postprocess (Dilution or dialysis) to tailor the osmotic pressure of hydrogels could be a necessary step before mixed with cells. Thus, kindly choosing the type and concentration of acidic solution is necessary for dECM bio-ink preparation. And a balance should be made between the digestion period, strength of acidic solution, as well as the size and concentration of the dECM powders. STATEMENT OF SIGNIFICANCE: The dECM bio-ink has been widely used in 3D cell printing for tissue engineering and organ modelling. In this study, we found that different types of acid have different digestion and dissolution status for the dECM materials. A much softer tendon derived dECM hydrogel with lower stiffness could facilitate the cellular spreading, proliferation and tendon differentiation. We also demonstrated that the osmotic pressure should be taken care of in the preparation of dECM bio-ink with 0.5 M acetic acid. Thus, kindly choosing the type and concentration of acidic solution is necessary for dECM bio-ink preparation.
脱细胞细胞外基质 (dECM) 水凝胶因其良好的细胞相容性和仿生特性，正越来越多地被用于三维细胞打印的生物墨水。生物墨水的渗透压和刚度是影响打印细胞生物学功能的重要因素。然而，人们对 dECM 生物墨水的渗透压和刚度关注甚少。在这里，我们比较了在肌腱衍生的 dECM 生物墨水的生物制造中三种常用的酸性溶液类型（0.5 M 乙酸、0.1 M 盐酸和 0.02 M 盐酸）用于 3D 细胞打印。我们发现，低 pH 值的 0.1 M 盐酸可以加速 dECM 粉末的消化过程。这会导致 dECM 水凝胶的存储模量小于 100 Pa，变得非常柔软。这种柔软的 dECM 水凝胶有利于封装在其中的干细胞的扩散和增殖。与另外两种更硬的 dECM 水凝胶相比，它还显示出更好的肌腱诱导能力。然而，这种过度消化的 dECM 水凝胶由于随着培养时间的推移会收缩，因此更加不稳定。对于由 0.5 M 乙酸制成的 dECM 生物墨水，生物墨水的高渗状态导致细胞活力率非常低。在与细胞混合之前，对水凝胶的渗透压进行后处理（稀释或透析）可能是必要的步骤。因此，在制备 dECM 生物墨水时，选择酸性溶液的类型和浓度是必要的。并且应该在消化时间、酸性溶液的强度以及 dECM 粉末的大小和浓度之间取得平衡。
dECM 生物墨水已广泛用于组织工程和器官建模的 3D 细胞打印。在这项研究中，我们发现不同类型的酸对 dECM 材料有不同的消化和溶解状态。具有较低刚度的更柔软的肌腱衍生 dECM 水凝胶可以促进细胞的扩散、增殖和肌腱分化。我们还证明，在制备 0.5 M 乙酸的 dECM 生物墨水时，应注意渗透压。因此，在制备 dECM 生物墨水时，选择酸性溶液的类型和浓度是必要的。
