MOLM-13 Xenograft Rat Model Service for Leukemia

The MOLM-13 Xenograft Rat Model Service for Leukemia provides a disseminated acute myeloid leukemia platform driven by FLT3-ITD oncogenic signaling, enabling robust preclinical evaluation of targeted agents against aggressive hematologic malignancies. Alfa Cytology constructs and manages every MOLM-13 cohort with meticulous attention to cell viability, host conditioning, and longitudinal disease monitoring, ensuring your pharmacodynamic and efficacy readouts are grounded in reproducible tumor kinetics from engraftment through endpoint.

Overview of MOLM-13 Xenograft Rat Model for Leukemia

The MOLM-13 cell line was established in 1995 from the peripheral blood of a 20-year-old male patient at relapse of acute monocytic leukemia (FAB M5a) that had evolved from an antecedent myelodysplastic syndrome (MDS, refractory anemia with excess of blasts). The line harbors a heterozygous internal tandem duplication (ITD) of the FLT3 receptor tyrosine kinase, a mutation present in approximately 30% of AML patients and associated with inferior prognosis. Additionally, MOLM-13 carries an occult chromosomal insertion, ins(11;9)(q23;p22p23), generating a KMT2A-MLLT3 (MLL-AF9) fusion transcript, alongside a CBL deltaExon8 mutation and trisomy 8. This composite molecular architecture renders the model exceptionally relevant for interrogating FLT3-directed therapeutics, combination strategies with BCL-2 antagonists, and resistance mechanisms arising from kinase domain mutations.

Fig 1. MOLM-13-Luc in vivo imaging, survival curves, and CAR-T bone marrow infiltration. (Li, Ke-xin, et al., 2022)

In vivo, MOLM-13 exhibits an aggressive disseminated growth pattern following intravenous engraftment, with leukemic blasts rapidly colonizing the bone marrow, spleen, and peripheral circulation. The model recapitulates hallmark features of human AML including progressive cytopenia, splenomegaly, and systemic morbidity, while offering the practical advantage of luciferase-enabled whole-body bioluminescence imaging for real-time tumor burden quantification. Its well-defined immunophenotype—CD33⁺ CD15⁺ CD4⁺ CD34⁻ CD14⁻—permits flow cytometric tracking of engraftment and lineage fidelity throughout the study, making it an indispensable tool for preclinical hematology-oncology research.

Cell Line Information: MOLM-13

The MOLM-13 human acute myeloid leukemia cell line is among the most extensively characterized AML models in contemporary hematologic research. Established from a patient with MDS-evolved AML-M5a, the line preserves a stable molecular and immunophenotypic profile that supports reproducible xenograft development in immunodeficient hosts. The table below summarizes the defining characteristics of this line.

Our Services

Alfa Cytology deploys a purpose-built hematology-oncology platform for MOLM-13 xenograft studies, combining SCID rat host conditioning, sterile tail vein injection protocols, and multi-parameter flow cytometry with bioluminescence imaging to track disseminated disease in real time. Our capabilities extend from single-agent efficacy screens to complex combination designs, delivering GLP-ready data packages that capture survival kinetics, bone marrow blast burden, and splenic infiltration metrics essential for advancing your AML therapeutic candidate.

Workflow of MOLM-13 Xenograft Rat Model Construction

Generation of a disseminated MOLM-13 leukemia model in immunocompromised rats demands stringent cell quality assurance, precise intravenous delivery, and systematic hematologic surveillance to achieve consistent engraftment and biologically meaningful endpoints. The workflow below delineates the standardized procedure for establishing MOLM-13-bearing rat cohorts.

1. Cell Line Resuscitation & Expansion. Cryopreserved MOLM-13 cells are thawed rapidly in a 37°C water bath and transferred to pre-warmed RPMI 1640 + 20% FBS. Following centrifugation, cells are resuspended in complete growth medium and cultured at 37°C, 5% CO₂. Identity is verified by STR profiling, and mycoplasma negativity is confirmed by PCR. Cells are expanded to log-phase density (0.5–1.5 × 10⁶ cells/ml) with >95% viability prior to inoculum preparation.
2. Host Conditioning. Immunodeficient recipient rats (SCID or SCID-beige variants) receive sublethal irradiation (2.25 Gy total body irradiation) or busulfan conditioning (20 mg/kg intraperitoneally) 24 hours prior to cell injection to ablate residual hematopoietic stem cells and enhance human blast engraftment. Conditioning method is selected based on institutional IACUC approval and study-specific tolerability data.
3. Inoculum Preparation & Viability Confirmation. MOLM-13 cells are harvested from exponential-phase cultures, washed twice in sterile ice-cold PBS, and resuspended at a concentration of 5 × 10⁶ cells/ml in PBS supplemented with 2% FBS. Cell viability and concentration are reconfirmed by trypan blue exclusion and automated cell counting; only suspensions with >95% viability and <5% aggregates are approved for injection.
4. Tail Vein Injection. Rats are briefly restrained in a dorsal recumbent position with the tail warmed under a heat lamp to promote vasodilation. A 26-gauge needle attached to a 1 mL syringe is inserted into the lateral tail vein at a shallow angle, and 200–500 µL of cell suspension (delivering 1–5 × 10⁶ cells) is administered slowly over 30–60 seconds. Hemostasis is achieved by gentle digital pressure; the injection site is inspected for extravasation.
5. Post-Injection Monitoring & Supportive Care. Animals are returned to warmed recovery cages and observed for acute distress for 2 hours post-injection. Daily health assessments include body weight, posture, hydration status, and peripheral blood smear evaluation. Subcutaneous fluid supplementation is provided if dehydration or weight loss exceeds 10% of baseline.
6. Engraftment Verification & Disease Monitoring. Peripheral blood is collected via saphenous venipuncture at days 7, 14, and 21 post-engraftment. Flow cytometry quantifies human CD33⁺/CD15⁺ leukemic blasts as a percentage of total mononuclear cells. For luciferase-expressing MOLM-13 variants, whole-body bioluminescence imaging (IVIS) is performed weekly following intraperitoneal luciferin injection (150 mg/kg) to visualize systemic tumor burden and organ-specific colonization.
7. Endpoint Assessment & Tissue Harvest. Study endpoints are reached upon 20% body weight loss, sustained lethargy, hind limb paralysis, or moribund status. Animals are humanely euthanized under deep isoflurane anesthesia. Bone marrow is flushed from femurs and tibias; spleen, liver, lung, and peripheral blood are collected. Specimens are processed for flow cytometric enumeration of human blast infiltration, histopathology (H&E, myeloperoxidase IHC), and molecular profiling of resistance mutations.

Fig 2. MOLM-13 Xenograft Rat Model construction workflow.

Case Study-MOLM-13 Xenograft Rat Model Development

In a recent preclinical program, Alfa Cytology established a disseminated MOLM-13 xenograft cohort in SCID rats to evaluate the efficacy of a next-generation FLT3 inhibitor administered as monotherapy and in combination with a BCL-2 antagonist. Following busulfan conditioning and tail vein injection of 2 × 10⁶ luciferase-labeled MOLM-13 cells, engraftment was confirmed by bioluminescence imaging at day 7, at which point animals were randomized into vehicle, single-agent, and combination treatment arms. Weekly IVIS tracking revealed differential tumor burden trajectories across cohorts, with the combination arm showing sustained signal reduction relative to monotherapy. At study termination, bone marrow flow cytometry demonstrated lower human CD33⁺ blast percentages in treated animals, while splenic weights and histopathological myeloperoxidase staining corroborated reduced organ infiltration. Pharmacokinetic sampling confirmed target plasma exposures, and ex vivo kinase profiling of harvested blasts provided mechanistic insight into residual FLT3 phosphorylation status. These preclinical findings furnished the sponsor with a comprehensive dataset to support continued development of the combination regimen toward formal toxicology assessment.

Why Choose Alfa Cytology?

Preclinical leukemia modeling demands specialized expertise in hematopoietic cell handling, immunodeficient host management, and multi-modal disease tracking. Alfa Cytology differentiates its MOLM-13 service through the following capabilities:

• Dedicated hematology-oncology team with extensive experience in SCID rat conditioning, sterile tail vein injection, and post-engraftment supportive care, ensuring high engraftment rates and minimal procedure-related mortality.
• Flexible model configurations including wild-type MOLM-13, luciferase-expressing variants, and FLT3-TKD resistant sublines to address mechanistic, efficacy, and resistance questions within a single study framework.
• Integrated in vivo imaging platform combining whole-body bioluminescence (IVIS) with small-animal MRI for anatomical localization of bone marrow, splenic, and hepatic leukemic infiltration.
• Comprehensive hematologic analytics encompassing peripheral blood smears, complete blood counts, multi-color flow cytometry (human CD33/CD15/CD34/CD117), and colony-forming unit assays for stem cell activity assessment.
• GLP-compliant histopathology and molecular pathology suite delivering H&E, myeloperoxidase IHC, TUNEL apoptosis quantification, and digital image analysis for objective tumor burden scoring across hematopoietic organs.
• Regulatory-ready documentation with IACUC-approved protocols, full chain-of-custody tracking, and audit-compliant data packages designed to streamline IND submission and investor due diligence.

Contact Us

Whether your AML program targets FLT3-ITD signaling, explores BCL-2 combination strategies, or seeks to overcome kinase inhibitor resistance, Alfa Cytology offers the preclinical infrastructure and scientific depth to advance your compound with precision. Reach out to us today to discuss your MOLM-13 xenograft model requirements, and let our hematology-oncology team design a study that generates the definitive preclinical evidence your development pipeline demands.

For research use only. Not intended for any clinical use.