骨關節炎（OA）是一種慢性退行性疾病，主要影響老年人，導致關節不適、活動範圍受限和關節不穩定。 OA最常見的症狀之一是軟骨缺陷。隨著老齡人口的增長，OA的患病率預計會上升，對未來的醫療系統提出了重大挑戰。

為解決這個問題，研究人員一直在探索軟骨組織工程作為替代受損軟骨組織的有希望的方法。這一領域涉及使用生物材料和支架，以及細胞和生長因子，促進組織再生。水凝膠是由交聯聚合物組成的三維網絡，具有高含水量的彈性和光滑表面。它們密切模擬了軟骨的天然細胞外基質，並為細胞增殖和分化提供了有利環境。
明膠丙烯酰基（GelMA）是從天然明膠中提取的，具有良好的生物相容性。它可以支持細胞粘附和增殖，使其適用於促進軟骨再生。聚丙烯酰胺（PAM）為水凝膠提供機械穩定性，確保它能夠承受關節運動帶來的機械應力。多巴胺以其與各種基質的強粘附性而聞名，將其納入水凝膠中可以增強其粘附性能。

本研究使用GelMA-PAM-多巴胺可注射水凝膠，將GelMA、PAM和多巴胺結合起來，相比純GelMA或PAM水凝膠，它提供了更好的細胞粘附性和組織粘附性。具有0.99 MPa的壓縮模量，表明具備機械穩定性，並具有10 kPa的高組織粘附強度，該水凝膠顯示了在軟骨修復和再生方面的潛力。使用軟骨細胞的體外研究顯示，與單獨的GelMA相比，含多巴胺的水凝膠進一步增強了細胞存活率。這些發現凸顯了GelMA-多巴胺-PAM可注射水凝膠在促進細胞附著、擴展和增殖方面的巨大潛力，使其成為組織工程的有希望生物材料。
此外，GelMA-多巴胺-PAM表現出較長的降解時間，在兩週內保留了70%以上的初始重量，適合長期支架和組織工程構建。 PAM的納入增強了GelMA的機械穩定性，而GelMA-多巴胺-PAM在生理溫度下保持其機械特性。此外，GelMA-多巴胺-PAM始終顯示出比GelMA和GelMA-PAM更高的細胞粘附性，表明其支持和促進細胞生長的能力。這些有利特性使GelMA-多巴胺-PAM成為組織工程應用的有希望候選材料。

總的來說，開發包含GelMA、PAM和多巴胺的可注射水凝膠在軟骨組織工程領域提供了一種有希望的方法。需要進一步的研究和評估來確定這種水凝膠在骨關節炎患者軟骨修復方面的長期療效、安全性和臨床可行性。

Osteoarthritis (OA) is a chronic degenerative disease that primarily affects the elderly, leading to joint discomfort, limited range of motion, and joint instability. One of the most common symptoms of OA is cartilage defects. As the aging population continues to grow, the prevalence of OA is expected to rise, presenting significant challenges to future healthcare systems.
Cartilage tissue engineering became a promising approach to replace damaged cartilage tissue. This field involves the use of biomaterials and scaffolds, along with cells and growth factors, to facilitate tissue regeneration. Hydrogels are three-dimensional networks of crosslinked polymers that possess elastic and smooth surfaces with high water content. They closely mimic the natural extracellular matrix of cartilage and provide a favorable environment for cell proliferation and differentiation.
Gelatin Methacryloyl (GelMA) is derived from natural gelatin and has excellent biocompatibility. It can support cell adhesion and proliferation, making it suitable for promoting cartilage regeneration. Polyacrylamide (PAM) offers mechanical stability to the hydrogel, ensuring that it can withstand the mechanical stresses imposed by joint movement. Dopamine is known for its strong adhesion to various substrates and incorporating it into hydrogels can enhance their adhesive properties.
The GelMA-PAM-dopamine injectable hydrogel, combining GelMA, PAM, and dopamine was used in this study, which offered superior cell adhesion and tissue adhesion compared to pure GelMA or PAM hydrogels. With a compressive modulus of 0.99 MPa, indicating mechanical stability, and a high tissue adhesive strength of 10 kPa, this hydrogel demonstrates its potential for cartilage repair and regeneration. In vitro studies using chondrocytes reveal that the hydrogel with dopamine further enhances cell viability compared to pure GelMA alone. These findings highlight the significant potential of the GelMA-DA-PAM injectable hydrogel in promoting cell attachment, spreading, and proliferation, making it a promising biomaterial for tissue engineering. Additionally, GelMA-DA-PAM exhibits an extended degradation time, retaining over 70% of its original weight for two weeks, making it suitable for long-lasting scaffolds and tissue engineering constructs. The incorporation of PAM enhances the mechanical stability of GelMA, and GelMA-DA-PAM maintains its mechanical properties at physiological temperature. Moreover, GelMA-DA-PAM consistently demonstrates higher cell adhesion than GelMA and GelMA-PAM, indicating its capacity to support and stimulate cell growth. These advantageous characteristics make GelMA-DA-PAM a promising candidate for tissue engineering applications.
Overall, the development of injectable hydrogels incorporating GelMA, PAM, and dopamine presents a promising approach in the field of cartilage tissue engineering. Further research and evaluation are required to ascertain the long-term efficacy, safety, and clinical feasibility of this hydrogel for cartilage repair in patients with osteoarthritis.

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