Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.
PLoS One. 2024 Feb 28;19(2):e0298390. doi: 10.1371/journal.pone.0298390. eCollection 2024.
Although highly conserved in structure and function, many (patho)physiological processes of the mammary gland vary drastically between mammals, with mechanisms regulating these differences not well understood. Large mammals display variable lactation strategies and mammary cancer incidence, however, research into these variations is often limited to in vitro analysis due to logistical limitations. Validating a model with functional mammary xenografts from cryopreserved tissue fragments would allow for in vivo comparative analysis of mammary glands from large and/or rare mammals and would improve our understanding of postnatal development, lactation, and premalignancy across mammals. To this end, we generated functional mammary xenografts using mammary tissue fragments containing mammary stroma and parenchyma isolated via an antibody-independent approach from healthy, nulliparous equine and canine donor tissues to study these species in vivo. Cryopreserved mammary tissue fragments were xenotransplanted into de-epithelialized fat pads of immunodeficient mice and resulting xenografts were structurally and functionally assessed. Preimplantation of mammary stromal fibroblasts was performed to promote ductal morphogenesis. Xenografts recapitulated mammary lobule architecture and contained donor-derived stromal components. Mammatropic hormone stimulation resulted in (i) upregulation of lactation-associated genes, (ii) altered proliferation index, and (iii) morphological changes, indicating functionality. Preimplantation of mammary stromal fibroblasts did not promote ductal morphogenesis. This model presents the opportunity to study novel mechanisms regulating unique lactation strategies and mammary cancer induction in vivo. Due to the universal applicability of this approach, this model serves as proof-of-concept for developing mammary xenografts for in vivo analysis of virtually any mammals, including large and rare mammals.
尽管乳腺的结构和功能在很大程度上是保守的，但许多（病理）生理过程在哺乳动物之间差异很大，而调节这些差异的机制尚未得到很好的理解。大型哺乳动物表现出不同的泌乳策略和乳腺癌症发病率，然而，由于物流限制，这些变化的研究往往仅限于体外分析。通过冷冻组织碎片的功能性乳腺异种移植验证模型，将允许对来自大型和/或稀有哺乳动物的乳腺进行体内比较分析，并提高我们对跨哺乳动物的产后发育、泌乳和癌前状态的理解。为此，我们使用通过抗体独立方法从健康、未产的马和犬供体组织中分离的乳腺基质和实质的乳腺组织片段生成功能性乳腺异种移植体，以在体内研究这些物种。将冷冻保存的乳腺组织碎片异种移植到免疫缺陷小鼠去上皮化的脂肪垫中，并对异种移植体进行结构和功能评估。进行乳腺基质成纤维细胞的预植入以促进导管形态发生。异种移植体重现了乳腺小叶结构，并包含供体衍生的基质成分。催乳激素刺激导致（i）泌乳相关基因的上调，（ii）增殖指数的改变，和（iii）形态变化，表明其具有功能性。乳腺基质成纤维细胞的预植入并未促进导管形态发生。该模型提供了研究调节独特泌乳策略和乳腺癌症诱导的新机制的机会。由于该方法具有普遍适用性，该模型可作为用于活体分析几乎任何哺乳动物（包括大型和稀有哺乳动物）的乳腺异种移植的概念验证。
