Techniques for the generation of humanized mouse models for immuno-oncology

Engraftment of adult hematopoietic stem and progenitor cells in a novel model of humanized mice

Pre-clinical use of humanized mice transplanted with CD34+ hematopoietic stem and progenitor cells (HSPCs) is limited by insufficient engraftment with adult non-mobilized HSPCs. Here, we developed a novel immunodeficient mice based on NOD-SCID-Il2γc-/- (NSG) mice to support long-term engraftment with human adult HSPCs. As both Flt3L and IL-6 are critical for many aspects of hematopoiesis, we knock-out mouse Flt3 and knock-in human IL6 gene. The resulting mice showed an increase in the availability of mouse Flt3L to human cells and a dose-dependent production of human IL-6 upon activation. Upon transplantation with low number of human HSPCs from adult bone marrow, these humanized mice demonstrated a significantly higher engraftment with multilineage differentiation of human lymphoid and myeloid cells, and tissue colonization at one year after adult HSPC transplant. Thus, these mice enable studies of human hematopoiesis and tissue colonization over time and may facilitate building autologous models for immuno-oncology studies.

Progress in building clinically relevant patient-derived tumor xenograft models for cancer research

Patient-derived tumor xenograft (PDX) models, a method involving the surgical extraction of tumor tissues from cancer patients and subsequent transplantation into immunodeficient mice, have emerged as a pivotal approach in translational research, particularly in advancing precision medicine. As the first stage of PDX development, the patient-derived orthotopic xenograft (PDOX) models implant tumor tissue in mice in the corresponding anatomical locations of the patient. The PDOX models have several advantages, including high fidelity to the original tumor, heightened drug sensitivity, and an elevated rate of successful transplantation. However, the PDOX models present significant challenges, requiring advanced surgical techniques and resource-intensive imaging technologies, which limit its application. And then, the humanized mouse models, as well as the zebrafish models, were developed. Humanized mouse models contain a human immune environment resembling the tumor and immune system interplay. The humanized mouse models are a hot topic in PDX model research. Regarding zebrafish patient-derived tumor xenografts (zPDX) and patient-derived organoids (PDO) as promising models for studying cancer and drug discovery, zPDX models are used to transplant tumors into zebrafish as novel personalized medical animal models with the advantage of reducing patient waiting time. PDO models provide a cost-effective approach for drug testing that replicates the in vivo environment and preserves important tumor-related information for patients. The present review highlights the functional characteristics of each new phase of PDX and provides insights into the challenges and prospective developments in this rapidly evolving field.

Isolation of Viable Single Cells With High Yield and Purity Using a Small Amount of Human Kidney Tissue Biopsy

Objective: Establishment of an efficient method of preparing human kidney single cell suspension, using a very small amount of tissue puncture. Methods: Samples of human kidney tissue puncture were cut into pieces, and then 80 μL of the digestive enzyme were added to each punctured tissue to induce enzymatic digestion. The enzyme combination is composed of collagenases, DNase and hyaluronidase and the sample was incubated 20 min at 37°C. The obtained cell suspension was filtered through a 70 μm cell strainer, centrifuged at 300 g for 5 min and the supernatant was removed, then the pellet was resuspended in 3 ml of DMEM (Dulbecco's Modified Eagle's Medium). Cell suspension was sorted and purified by flow sorting to remove dead cells and obtain a cell suspension with higher viability rate. Results: We found that 1) diverse single cells of human kidney can be obtained by the digestive enzyme, as observed under the light microscope, with different sizes, normal cell morphology and good dispersion. 2) (2-3) × 10⁶ single cells can be extracted from one fresh punctured kidney tissue of about 10 mg, with a cell viability rate of more than 80%. Conclusion: In this work we generated a comprehensive and high-resolution single-cell method, which is simple and efficient for preparing single cell suspension from a minimal amount of human kidney tissue. This method can facilitate the study of renal cell biology and the pathogenesis of kidney diseases.

Leveraging Patient-Derived Models for Immunotherapy Research

As cancer immunotherapies become mainstream for the treatment of many different cancer types and the numbers of new agents continue to increase, the need for experimental models is also rising. An approach to develop and study models for immune-oncology that has garnered intense interest in recent years is that of using patient-derived models. Patient-derived models can recapitulate many of the features and heterogeneity of the corresponding human tumors. Historically these models have been used to study cancer cell-intrinsic properties of tumors and drugs that target tumor cells directly. In recent years, increasing recognition of the role immune cells play in cancer and how these represent good therapeutic targets has led to efforts to optimize and use patient-derived models for cancer immunotherapy studies. Patient-derived models are now being used to study the properties of cancer cells that modulate their ability to respond to immune stimulation. Further efforts are underway to use and develop patient-derived models that incorporate human immune cells in vitro and in vivo (humanized mice) so that cancer cell-immune cell interactions can be studied in the context of cancer immunotherapies. As these models are further refined, leveraging patient-derived models for cancer immunotherapy research can provide insight into mechanisms of sensitivity and resistance to cancer immunotherapies, uncover new targets, reveal how specific agents work, and be used to evaluate the antitumor efficacy of therapeutic regimens.