5T33 / 5T33-luc Orthotopic Mouse Model Service for Multiple Myeloma (MM)

The 5T33 / 5T33-luc orthotopic mouse model transplants a spontaneously arising murine multiple myeloma into its syngeneic C57BL/KaLwRij host, where malignant plasma cells home to the bone marrow and secrete measurable IgG2b paraprotein — recreating the paraproteinemia that defines and monitors human MM inside a fully immunocompetent animal. Alfa Cytology delivers this aggressive, reproducible platform with optional irradiation preconditioning, serum protein electrophoresis-based disease tracking, quantitative luciferase imaging in vivo, and benchmark arms from the published CDK4/6–bortezomib and carfilzomib combination record, so proteasome, cell-cycle, and immunotherapy strategies are tested on the reference syngeneic MM system.

Overview of 5T33 / 5T33-luc Orthotopic Mouse Model for Multiple Myeloma (MM)

The 5T series originated with Radl and colleagues at TNO in the Netherlands, who observed that aging C57BL/KaLwRij mice spontaneously develop a disease strikingly faithful to human multiple myeloma — bone marrow plasma cell proliferation, tumor-associated paraprotein, and a predisposition rooted in the strain's germline (the KaLwRij genome has since been fully sequenced to map this B-cell immortalization trait). 5T33 is the aggressive, rapidly progressing variant of this family, classically propagated by intravenous transfer of cells from diseased bone marrow into young syngeneic recipients, which develop full disease in three to four weeks. When Manning and colleagues adapted 5T33 to continuous in vitro culture in 1992 (the 5T33MMvt form), they documented a maximum doubling time near 25 hours, cytoplasmic IgG2b paraprotein in over 90% of cells, and extraordinary tumorigenicity: as few as 500 cells induced paralysis and death by day 36, with kinetics that scale predictably with dose. After intravenous inoculation of 5 × 10⁵ cells, tumor cells are readily identified in bone marrow within two weeks and disseminate widely by three, with the spleen, liver, and axial skeleton as characteristic sites — disease progression that clinically manifests as paraplegia from vertebral involvement.

Fig 1. Copy number analysis across the 5TMM-derived cell lines (5TGM1, 5T33, 5T2) showing common losses (Brca2, Flt3, Rac1, Fgfr3, Card11) and gains (Crtc3, Idh2, Ntrk2), alongside pathway-focused changes in Ras/MAPK, PI3K/Akt, Jak/Stat, DNA repair and p53/cell cycle genes, providing the genomic framework distinguishing aggressive 5T33 from indolent 5T2. (Maes, Ken, et al., 2018)

Two features define the model's experimental identity. First, the paraprotein itself: serum IgG2b quantified by protein electrophoresis functions as a direct, non-invasive analog of the patient M-spike, allowing tumor burden to be tracked serially in the same animal — a capability human xenograft models approximate only with difficulty. Second, its benchmarked pharmacology: CDK4/6 inhibition with PD-0332991 suppressed tumor growth and extended survival from 25 to 35 days while sensitizing 5T33 to bortezomib, and modern protocols have established a bortezomib-resistant configuration in which irradiated recipients carry tumors that progress under 0.7 mg/kg weekly bortezomib — as well as carfilzomib and RNA polymerase I inhibitor combinations in vivo. Luciferase-tagged 5T33 (and the eGFP/HSV-tk configurations that preceded it) enables quantitative bioluminescence in vivo, with randomization by signal at days 7–14. Candidly, 5T33 does not develop the florid osteolytic lesions of its slower 5T2MM and 5TGM1 relatives (though cortical bone destruction occurs at invaded sites), so programs centered on bone disease should pair it accordingly — but for aggressive tumor-burden pharmacology in an intact immune system, few MM models match its speed, biomarker accessibility, and forty-year pedigree.

Cell Line Information: 5T33 / 5T33-luc

The cultured form 5T33MMvt (RRID CVCL_G080) grows in vitro as single cells or small clusters loosely adherent to a stromal layer, doubling in about 25 hours, with cytoplasmic IgG2b paraprotein in more than 90% of cells and documented continuous culture beyond 34 passages. The immunocompetent C57BL/KaLwRij host preserves full tumor–immune interplay, and homing depends on documented chemoattractants — IGF-1 and laminin-1 — with an adhesion repertoire (LFA-1, H-CAM/CD44 variant, VLA-4, VLA-5) that mirrors human myeloma homing biology. The 5T33-luc derivative adds firefly luciferase for quantitative imaging in vivo, with monoclonal selection of high-signal clones in vitro recommended for uniform bioluminescence.

Our Services

MM studies live or die by burden measurement — and 5T33 offers two orthogonal rulers: serum IgG2b paraprotein by protein electrophoresis, the true analog of the clinical M-spike, and whole-body bioluminescence from luciferase-tagged cells. Alfa Cytology runs 5T33 programs with both readouts in parallel, optional irradiation preconditioning where engraftment standardization matters, paraplegia-savvy humane-endpoint protocols, benchmark arms from the CDK4/6–bortezomib and bortezomib-resistance literature, and honest pairing guidance for bone-disease questions — so your proteasome, cell-cycle, or immunotherapy program measures what matters, the way the field measures it.

Workflow of 5T33 / 5T33-luc Orthotopic Mouse Model Construction

5T33 model construction is compact and fast — full disease in three to four weeks — but its power depends on disciplined burden measurement and humane-endpoint vigilance for paraplegia. The workflow below follows the validated syngeneic configuration from cell preparation through paraprotein- and imaging-anchored endpoints.

1. Cell Expansion and Quality Control: 5T33 or 5T33-luc cells are expanded in vitro (5T33MMvt form) in RPMI-1640-based medium as loosely adherent clusters, keeping density within the productive window; batches are confirmed mycoplasma-negative, verified for IgG2b paraprotein expression in over 90% of cells, and — for luciferase configurations — monoclonal high-signal clones are confirmed by in vitro assay.
2. Host Selection and Optional Preconditioning: C57BL/KaLwRij mice, 6–8 weeks of age, are acclimatized and health-screened; where engraftment standardization is required (including bortezomib-resistant configurations), mice receive 3 Gy irradiation in two fractions six hours apart one day before transplantation, with dietary supplementation during recovery.
3. Intravenous Inoculation: A single-cell suspension is prepared in serum-free medium and injected via the tail vein; the standard challenge is 0.5 × 10⁶ cells, with dose titration available given the documented relationship between inoculum and disease kinetics.
4. Engraftment Verification and Randomization: 5T33-luc cohorts are imaged by bioluminescence in vivo (200 µL of 15 mg/mL D-luciferin intraperitoneally, five minutes pre-imaging) at days 7–14 and randomized by signal; non-luc configurations are stratified by body weight and condition.
5. Treatment Administration: Test agents are dosed on study-defined schedules — benchmark regimens include weekly bortezomib or carfilzomib, CDK4/6 partners, and RNA Pol I inhibitors — with body weight and gait monitored daily for early paraplegia signals.
6. Dual-Readout Disease Monitoring: Disease burden is tracked weekly by serum protein electrophoresis for IgG2b paraprotein (the M-spike analog) and — in luciferase studies — by bioluminescence quantification in vivo, giving each study two independent kinetics curves.
7. Survival Follow-Up and Humane Endpoints: Animals are monitored for the classic vertebral endpoint (paraplegia) and overall morbidity, with euthanasia at predefined criteria and Kaplan–Meier analysis across arms.
8. Endpoint Analysis and Reporting: At termination, bone marrow is flushed from femurs, tibiae, and crushed vertebrae, tumor load is quantified by flow cytometry (idiotype or luciferase/eGFP markers), spleen and liver are weighed and examined for infiltration, serum paraprotein is finalized, micro-CT or histomorphometry documents bone status at invaded sites, and bioluminescence, paraprotein, flow cytometry, and survival data are compiled into the final report.

Fig 2. 5T33 / 5T33-luc orthotopic mouse model construction workflow.

Case Study-5T33 / 5T33-luc Orthotopic Mouse Model Development

The 5T33 platform is the most established aggressive syngeneic MM system in the literature, and it has carried a broad range of Alfa Cytology client programs — proteasome inhibitor benchmarking and bortezomib-resistance configurations, CDK4/6 and cell-cycle combinations, immunotherapy evaluation in fully immunocompetent hosts, and angiogenesis and homing-biology studies exploiting its documented IGF-1 and laminin-1 chemoattraction. Across these programs, readouts have combined paraprotein electrophoresis kinetics, bioluminescence imaging in vivo, and marrow-level flow cytometry with survival analysis. Anonymized case summaries and representative deliverable formats are available on request.

Why Choose Alfa Cytology?

5T33 combines speed, biomarker accessibility, and immunocompetence — three properties that demand precise execution to realize together. Alfa Cytology has operationalized all three.

• A forty-year syngeneic pedigree from the Radl 5T series — the reference immunocompetent MM system.
• Serum IgG2b paraprotein as a true M-spike analog, quantifiable serially by protein electrophoresis.
• Extreme tumorigenic sensitivity (as few as 500 cells lethal) with documented dose-dependent kinetics.
• Validated preconditioning and resistance configurations, including irradiation-standardized bortezomib-resistant cohorts.
• Dual non-invasive readouts: paraprotein electrophoresis and quantitative luciferase bioluminescence in vivo.
• Benchmark combination record — CDK4/6 inhibition extending survival 25→35 days and sensitizing to bortezomib.
• Paraplegia-aware humane-endpoint expertise with marrow, spleen, and vertebral endpoint workflows.

Contact Us

If your multiple myeloma program needs an immunocompetent model with a genuine serum biomarker, three-to-four-week kinetics, and a validated resistance pathway, the 5T33 / 5T33-luc orthotopic system is the field's reference — and Alfa Cytology runs it with the paraprotein and imaging rigor it deserves. Reach out to us to review preconditioning options, benchmark arms, and dual-readout monitoring designs, and receive a customized study quotation today.

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