Background/Objectives: Adipose tissue (AT) plays significant roles in energy storage, metabolite signaling, and immunomodulation. The understanding of its underlying mechanisms of dysregulation can provide insight into complex disease processes through analysis with histology, flow cytometry, metabolomics, and proteomics. Tissue sampling in the clinical setting has largely shifted towards minimally invasive approaches to improve factors such as patient satisfaction, post-operative recovery, and procedure length. In contrast, preclinical animal models continue to rely on more invasive methods until refined, minimally invasive techniques are developed and systematically assessed. To improve animal welfare and enhance clinical translatability, there is a critical need to reverse translate these approaches into animal models. Methods: Our study evaluated the feasibility and performance of a commercially available vacuum-assisted biopsy (VAB) device for AT sampling in a preclinical nonhuman primate (NHP) model. Six rhesus NHPs successfully underwent three serial AT biopsies with a VAB device (n = 18). Results: All animals recovered without any serious or unexpected adverse events. The amount of adipose tissue collected per biopsy (0.5–2.7 g) was proportional to the number of individual tracks. Isolation of the stromal vascular fraction (SVF) from a subset of samples (n = 6) yielded 0.41 ± 0.12 × 10⁶ cells/g of tissue. Conclusions: The minimally invasive VAB technique is a safe and reliable method of AT collection in NHPs. This feasibility study demonstrated adequate volumes of tissue cores that are suitable for typical, downstream research applications including immunologic studies and pathology, while improving animal welfare.

Weight change predicts mortality and graft loss in human kidney transplant recipients, yet post-transplant weight dynamics in nonhuman primate (NHP) transplant models remain poorly characterized despite their importance in preclinical immunosuppression and tolerance studies. By failing to account for demographic-specific growth patterns, static weight thresholds reduce interpretability and mask early biological signals of post-transplant morbidity. We analyzed 879 weights from 40 NHPs undergoing allogeneic kidney transplantation, with follow-up censored at 1-year post transplant. Expected post-transplant trajectories were estimated using demographic-stratified linear mixed-effects models with natural splines. Deviations from predicted trajectories defined pathologic weight loss. Associations with adverse events were evaluated using time-dependent cause-specific Cox regression. Expected trajectories differed significantly by age and species, with greater anticipated weight gain among younger animals. Each one-standard deviation decrease below predicted weight was associated with a two-fold increased hazard of adverse events. The model predicted pathological deviations before symptom onset and humane endpoints. Longitudinal weight trajectory modeling represents a computational modeling-based new approach methodology (NAM) that improves interpretability of preclinical weight endpoints. Defining risk relative to expected trends enables earlier and more precise prediction of adverse events, supports adaptive intervention including immunosuppression de-escalation and infection-directed management.