Custom Technology (United States)

While imaging matrix-associated stem cell transplants aimed for cartilage repair in a rodent arthritis model, we noticed that some transplants formed locally destructive tumors. The purpose of this study was to determine the cause for this tumor formation in order to avoid this complication for future transplants. Adipose-derived stem cells (ADSC) isolated from subcutaneous adipose tissue were implanted into 24 osteochondral defects of the distal femur inten athymic rats and two immunocompetent control rats. All transplants underwent serial magnetic resonance imaging (MRI) up to 6weeks post-transplantation to monitor joint defect repair. Nine transplants showed an increasing size over time that caused local bone destruction (group 1), while 11 transplants in athymic rats (group 2) and 4 transplants in immunocompetent rats did not. We compared the ADSC implant size and growth rate on MR images, macroscopic features, histopathologic features, surface markers, and karyotypes of these presumed neoplastic transplants with non-neoplastic ADSC transplants. Implants in group 1 showed a significantly increased two-dimensional areaat week 2 (p = 0.0092), 4 (p = 0.003), and 6 (p = 0.0205) compared to week 0, as determined by MRI. Histopathological correlations confirmed neoplastic features in group 1 with significantly increased size, cellularity, mitoses, and cytological atypia compared to group 2. Six transplants in group 1were identified as malignant chondrosarcomas and three transplants as fibromyxoid sarcomas. Transplants in group 2 and immunocompetent controls exhibited normal cartilage features. Both groups showed a normal ADSC phenotype; however, neoplastic ADSC demonstrated a mixed population of diploid and tetraploid cells without genetic imbalance. ADSC transplants can form tumors in vivo. Preventive actions to avoid in vivo tumor formations may include karyotyping of culture-expanded ADSC before transplantation. In addition, serial imaging of ADSC transplants in vivo may enable early detection of abnormally proliferating cell transplants.

Flow cytometry has a multitude of applications in nearly all fields of biology. Newly described biological markers enable the creation of novel reagents which then aid in the elucidation of unique subsets of cells and their potential role in health and disease. In order to enable the simultaneous detection of an even greater number of parameters, the future progress of flow cytometry relies on advances in instrument engineering and the parallel development of new fluorophores. In order to address the issues of reagent reliability, reproducibility, and work-flow optimization, we have used the freeze-dry technique to stabilize pre-mixed, pre-optimized, multicolor 'cocktails' of antibodies within 12 × 75 mm flow cytometry tubes (Lyotube). In this study we describe several lyophilized stabilized reagent combinations that are functional for extended periods of time (18 months and beyond), and can be stored at ambient temperature, eliminating cold-chain requirements during transportation and storage. This improves precision and reduces the redundant labor and error-potential associated with mixing antibodies to create "home-brew" cocktails. We have stained different types of samples including normal and leukemic whole blood, bone marrow, and PBMCs, as well as cell lines, directly with BD Lyotube reagents: The data show comparable and consistent performance of multiple batches of dehydrated, stabilized mixtures of antibodies and their liquid counterparts. The approach we describe here, the Lyotube, facilitates the improvement and implementation of standardization measures in clinical settings and in multi-site studies, a useful tool which can also be applied to determining the efficacy and safety of candidate therapeutics and vaccines. © 2016 International Clinical Cytometry Society.