Injectable hydrogels have gained popularity as a vehicle for the delivery of cells, growth factors, and other molecules to localize and improve their retention at the injection site, as well as for the mechanical bulking of tissues. However, there are many factors, such as viscosity, storage and loss moduli, and injection force, to consider when evaluating hydrogels for such applications. There are now numerous tools that can be used to quantitatively assess these factors, including for shear-thinning hydrogels because their properties change under mechanical load. Here, we describe relevant rheological tests and ways to measure injection force using a force sensor or a mechanical testing machine toward the evaluation of injectable hydrogels. Injectable, shear-thinning hydrogels can be used in a variety of clinical applications, and as an example we focus on methods for injection into the heart, where an understanding of injection properties and mechanical forces is imperative for consistent hydrogel delivery and retention. We discuss methods for delivery of hydrogels to mouse, rat, and pig hearts in models of myocardial infarction, and compare methods of tissue postprocessing for hydrogel preservation. Our intent is that the methods described herein can be helpful in the design and assessment of shear-thinning hydrogels for widespread biomedical applications.

中文翻译：

---

评估剪切稀化水凝胶作为可注射生物材料的方法

可注射的水凝胶已作为一种用于输送细胞，生长因子和其他分子以定位并改善其在注射部位的滞留以及用于组织的机械扩张的载体而受到欢迎。但是，在评估用于此类应用的水凝胶时，要考虑许多因素，例如粘度，存储和损耗模量以及注入力。现在有许多工具可用于定量评估这些因素，包括用于剪切稀化的水凝胶，因为它们的性质会在机械负载下发生变化。在这里，我们描述了相关的流变学测试以及使用力传感器或机械测试机测量注射力的方法，以评估可注射的水凝胶。可注射的剪切稀化水凝胶可用于多种临床应用，举一个例子，我们专注于向心脏内注射的方法，在这种方法中，必须了解注射特性和机械力才能保持一致的水凝胶递送和保留。我们讨论了在心肌梗塞模型中将水凝胶递送给小鼠，大鼠和猪心脏的方法，并比较了组织后处理对水凝胶保存的方法。我们的目的是，本文所述的方法可有助于设计和评估用于稀薄的水凝胶，以用于广泛的生物医学应用。并比较了用于水凝胶保存的组织后处理方法。我们的目的是，本文所述的方法可有助于设计和评估用于稀薄的水凝胶，以用于广泛的生物医学应用。并比较了用于水凝胶保存的组织后处理方法。我们的目的是，本文所述的方法可有助于设计和评估用于稀薄的水凝胶，以用于广泛的生物医学应用。