THP-1 Xenograft Rat Model Service for Leukemia

The THP-1 Xenograft Rat Model Service for Leukemia furnishes a well-characterized acute monocytic leukemia platform bearing the MLL-AF9 oncofusion, enabling rigorous preclinical assessment of differentiation-inducing agents, targeted small molecules, and combination regimens against M5-subtype malignancies. Alfa Cytology engineers each THP-1 study with exacting standards in cell authentication, host conditioning, and multi-modal disease tracking, translating complex hematologic biology into actionable pharmacodynamic and efficacy datasets that underpin your preclinical decision-making.

Overview of THP-1 Xenograft Rat Model for Leukemia

The THP-1 cell line was established in 1980 by Tsuchiya and colleagues from the peripheral blood of a one-year-old male patient at relapse of acute monocytic leukemia (FAB subtype M5). The line carries a balanced t(9;11)(p21;q23) chromosomal translocation that generates the KMT2A-MLLT3 (MLL-AF9) fusion oncogene, a molecular lesion frequently encountered in infant and therapy-related AML and strongly associated with aggressive disease course. In addition to this driver alteration, THP-1 cells exhibit monocytic features including phagocytic activity, lysozyme secretion, and responsiveness to differentiation stimuli such as phorbol 12-myristate 13-acetate (PMA), which triggers their maturation into macrophage-like adherent cells. This dual nature—retaining leukemic blast proliferative capacity while preserving differentiation plasticity—renders the model particularly valuable for studying lineage reprogramming therapies, epigenetic modulators, and agents that force terminal differentiation rather than direct cytotoxicity.

Fig 1. THP-1 cell morphology. (Yu, Fei, et al., 2024)

In vivo, THP-1 engrafts immunodeficient hosts with high efficiency following either subcutaneous or intravenous delivery, forming disseminated disease that colonizes the bone marrow, spleen, liver, and peripheral blood. The model recapitulates systemic leukemic burden with predictable kinetics, and when engineered with firefly luciferase reporter constructs, permits whole-body bioluminescence imaging for longitudinal quantification of tumor load and treatment response. Its distinctive immunophenotype—CD33⁺ CD13⁺ CD15⁺ CD4⁺ CD34⁻ CD14⁻ cyCD68⁺—enables precise flow cytometric enumeration of human blast infiltration across hematopoietic compartments, establishing THP-1 as a versatile substrate for preclinical leukemia research spanning drug screening, differentiation therapy, and innate immune modulation.

Cell Line Information: THP-1

The THP-1 human acute monocytic leukemia cell line stands as one of the most widely utilized hematologic models in both basic and translational research. Established over four decades ago, the line maintains a stable molecular identity and functional phenotype that supports reproducible xenograft development across immunodeficient rodent platforms. The table below enumerates the defining characteristics of this line.

Our Services

Alfa Cytology brings specialized hematology-oncology expertise to every THP-1 xenograft engagement, offering flexible delivery routes—subcutaneous for localized efficacy assessment or intravenous for disseminated disease modeling—paired with longitudinal bioluminescence imaging, multi-parameter flow cytometry, and GLP-compliant histopathology. Our integrated platform captures differentiation markers, blast burden kinetics, and organ-specific infiltration patterns, delivering audit-ready data packages that support your compound's progression from mechanistic validation toward IND-enabling studies.

Workflow of THP-1 Xenograft Rat Model Construction

Construction of a THP-1 leukemia xenograft in immunocompromised rats necessitates careful attention to cell line integrity, host immune status, and sterile technique to achieve consistent engraftment and biologically informative endpoints. The workflow below describes the standardized sequence for generating THP-1-bearing rat cohorts suitable for preclinical therapeutic evaluation.

1. Cell Line Resuscitation & Expansion. Cryopreserved THP-1 cells are rapidly thawed in a 37°C water bath and transferred to pre-warmed RPMI 1640 + 20% FBS. After centrifugation, cells are resuspended in complete medium containing 10% FBS, 2 mM L-glutamine, 10 mM HEPES, 1 mM sodium pyruvate, and 0.05 mM 2-mercaptoethanol. Identity is confirmed by STR profiling against the reference database, and mycoplasma negativity is verified by PCR. Cells are expanded to log-phase density (0.3–0.8 × 10⁶ cells/ml) with >95% viability prior to inoculum preparation.
2. Host Selection & Conditioning. Immunodeficient recipient rats (SCID, SCID-beige, or NOD-SCID variants) are acclimatized for at least 7 days. Where disseminated disease modeling is required, animals receive sublethal total body irradiation (2.0–2.5 Gy) or busulfan conditioning (20 mg/kg intraperitoneally) 24 hours prior to cell injection to deplete residual hematopoietic stem cells and enhance human blast engraftment.
3. Inoculum Preparation & Quality Check. THP-1 cells are harvested from exponential-phase cultures, washed twice in sterile ice-cold PBS, and resuspended at the target concentration—typically 1 × 10⁷ cells/ml for subcutaneous delivery or 1–2.5 × 10⁷ cells/ml for intravenous injection. Cell viability is reconfirmed by trypan blue exclusion, and aggregate formation is assessed microscopically; only single-cell suspensions with >95% viability are approved for in vivo use.
4. Tumor Cell Inoculation. For subcutaneous models, 2 × 10⁶ cells in 100–200 µL PBS are injected into the right flank using a 25-gauge needle. For disseminated leukemia models, rats are restrained with the tail warmed under a heat lamp to dilate the lateral tail vein; a 26-gauge needle is used to deliver 200–500 µL of cell suspension (2–5 × 10⁶ cells) slowly over 30–60 seconds. Hemostasis is achieved by gentle pressure, and the injection site is inspected for extravasation.
5. Post-Inoculation Monitoring & Supportive Care. Animals are returned to warmed recovery cages and observed for acute distress for 2 hours. Daily health checks include body weight, posture, hydration, and peripheral blood smear evaluation. Subcutaneous fluid supplementation and nutritional support are provided if weight loss exceeds 10% of baseline. Animals are housed in HEPA-filtered biocontainment caging to minimize opportunistic infection risk.
6. Longitudinal Disease Surveillance. Subcutaneous tumors are measured with digital calipers twice weekly. For disseminated models, peripheral blood is collected via saphenous venipuncture at days 7, 14, and 21; flow cytometry quantifies human CD33⁺/CD13⁺/CD15⁺ leukemic blasts as a percentage of total mononuclear cells. Luciferase-expressing THP-1 variants enable weekly whole-body bioluminescence imaging (IVIS) following intraperitoneal luciferin injection (150 mg/kg) to visualize systemic tumor burden and organ-specific colonization in real time.
7. Endpoint Assessment & Comprehensive Harvest. Study endpoints are triggered by 20% body weight loss, sustained lethargy, hind limb paralysis, or moribund condition. Under deep isoflurane anesthesia, animals are humanely euthanized. Bone marrow is aspirated from femurs and tibias; spleen, liver, lung, and peripheral blood are collected and weighed. Specimens are processed for flow cytometric blast enumeration, histopathology (H&E, myeloperoxidase IHC, CD68 macrophage staining), and molecular profiling of differentiation status and resistance mechanisms.

Fig 2. THP-1 Xenograft Rat Model construction workflow.

Case Study-THP-1 Xenograft Rat Model Development

In a recent preclinical initiative, Alfa Cytology established a disseminated THP-1 xenograft cohort in irradiated SCID rats to evaluate the differentiation-inducing potential of a novel histone deacetylase inhibitor combined with a low-dose demethylating agent. Following tail vein injection of 3 × 10⁶ luciferase-labeled THP-1 cells, engraftment was confirmed by bioluminescence imaging at day 10, at which point animals were randomized into vehicle, single-agent, and combination arms. Weekly IVIS tracking revealed divergent disease trajectories, with the combination cohort exhibiting sustained reduction in systemic photon flux relative to monotherapy. At study termination, bone marrow flow cytometry showed increased CD14⁺ and CD11b⁺ expression in treated animals, indicative of monocytic differentiation, while peripheral blood blast counts were markedly lower than in controls. Histopathological review demonstrated reduced splenic and hepatic infiltration in the combination group, accompanied by elevated myeloperoxidase staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positivity. Pharmacokinetic analysis confirmed target plasma exposures for both agents. These preclinical observations furnished the sponsor with a mechanistic rationale and efficacy signal to advance the combination toward formal toxicology evaluation.

Why Choose Alfa Cytology?

Preclinical leukemia modeling demands more than technical execution—it requires scientific insight into hematopoietic cell biology, immunodeficient host management, and the nuanced endpoints that differentiate a promising lead from a failed candidate. Alfa Cytology elevates its THP-1 service through the following distinctive capabilities:

• Specialized hematology team with deep expertise in monocytic leukemia cell handling, SCID rat conditioning, and post-engraftment supportive care, ensuring high take rates and minimal procedure-related attrition.
• Versatile model configurations spanning wild-type THP-1, luciferase-expressing variants, and PMA-differentiated macrophage controls to address efficacy, differentiation, and innate immune modulation questions within a unified study design.
• Integrated imaging and analytics platform combining whole-body bioluminescence (IVIS), small-animal MRI, multi-color flow cytometry (human CD33/CD13/CD15/CD14/CD11b), and complete blood count profiling for comprehensive disease characterization.
• Differentiation-focused histopathology suite delivering H&E, myeloperoxidase IHC, CD68 macrophage staining, TUNEL apoptosis quantification, and digital pathology scoring to capture both cytotoxic and lineage-reprogramming drug effects.
• Regulatory-compliant study conduct under IACUC-approved protocols with full chain-of-custody documentation, GLP-capable data packages, and audit-ready reports designed to support IND submission and investor presentations.
• Agile project management with biweekly scientific updates, real-time data dashboards, and direct access to study directors for protocol refinement and rapid troubleshooting throughout the engagement.

Contact Us

Whether your program seeks to differentiate leukemic blasts, target MLL-rearranged oncogenes, or modulate the innate immune microenvironment in monocytic leukemia, Alfa Cytology provides the preclinical infrastructure and scientific acumen to move your candidate forward. Contact us today to discuss your THP-1 xenograft model requirements, and let our hematology-oncology specialists craft a study that yields the definitive preclinical evidence your development strategy requires.

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