Hagey Laboratory for Pediatric Regenerative Medicine, Plastic and Reconstructive Surgery Division, Department of Surgery, Stanford University School of Medicine, California, USA.
Tissue Eng Part C Methods. 2013 Mar;19(3):227-32. doi: 10.1089/ten.TEC.2012.0371. Epub 2013 Jan 4.
Although autologous fat grafting has revolutionized the field of soft tissue reconstruction and augmentation, long-term maintenance of fat grafts is unpredictable. Recent studies have reported survival rates of fat grafts to vary anywhere between 10% and 80% over time. The present study evaluated the long-term viability of human fat grafts in a murine model using a novel imaging technique allowing for in vivo volumetric analysis.
Human fat grafts were prepared from lipoaspirate samples using the Coleman technique. Fat was injected subcutaneously into the scalp of 10 adult Crl:NU-Foxn1(nu) CD-1 male mice. Micro-computed tomography (CT) was performed immediately following injection and then weekly thereafter. Fat volume was rendered by reconstructing a three-dimensional (3D) surface through cubic-spline interpolation. Specimens were also harvested at various time points and sections were prepared and stained with hematoxylin and eosin (H&E), for macrophages using CD68 and for the cannabinoid receptor 1 (CB1). Finally, samples were explanted at 8- and 12-week time points to validate calculated micro-CT volumes.
Weekly CT scanning demonstrated progressive volume loss over the time course. However, volumetric analysis at the 8- and 12-week time points stabilized, showing an average of 62.2% and 60.9% survival, respectively. Gross analysis showed the fat graft to be healthy and vascularized. H&E analysis and staining for CD68 showed minimal inflammatory reaction with viable adipocytes. Immunohistochemical staining with anti-human CB1 antibodies confirmed human origin of the adipocytes.
Studies assessing the fate of autologous fat grafts in animals have focused on nonimaging modalities, including histological and biochemical analyses, which require euthanasia of the animals. In this study, we have demonstrated the ability to employ micro-CT for 3D reconstruction and volumetric analysis of human fat grafts in a mouse model. Importantly, this model provides a platform for subsequent study of fat manipulation and soft tissue engineering.
尽管自体脂肪移植已经彻底改变了软组织重建和填充领域，但脂肪移植的长期维持效果仍难以预测。最近的研究报告称，脂肪移植的存活率随时间推移在 10%到 80%之间变化。本研究采用一种新的成像技术，通过体内体积分析评估了人类脂肪移植物在小鼠模型中的长期存活能力。
采用科尔曼技术从脂肪抽吸样本中制备人类脂肪移植物。将脂肪注射到 10 只成年 Crl:NU-Foxn1(nu) CD-1 雄性小鼠的头皮下。注射后立即进行微计算机断层扫描（CT），然后每周进行一次。通过立方样条插值重建三维（3D）表面来呈现脂肪体积。还在不同时间点采集标本，并用苏木精和伊红（H&E）对巨噬细胞进行 CD68 染色，对大麻素受体 1（CB1）进行染色。最后，将样本在 8 周和 12 周时间点进行离体，以验证计算的微 CT 体积。
每周的 CT 扫描显示随着时间的推移，体积逐渐减少。然而，8 周和 12 周时间点的体积分析趋于稳定，分别显示平均 62.2%和 60.9%的存活率。大体分析显示脂肪移植物健康且有血管化。H&E 分析和 CD68 染色显示炎症反应轻微，有存活的脂肪细胞。用抗人 CB1 抗体进行免疫组化染色证实了脂肪细胞的人类起源。
评估自体脂肪移植物在动物体内命运的研究主要集中在非成像方式上，包括组织学和生化分析，这些方法需要对动物进行安乐死。在这项研究中，我们已经证明了在小鼠模型中使用微 CT 进行 3D 重建和人类脂肪移植物体积分析的能力。重要的是，该模型为后续的脂肪操作和软组织工程研究提供了一个平台。
