ATO-Supported CD34+ HSC Humanized BLT Models

Altogen Labs provides a CD34-positive hematopoietic stem cell humanized mouse platform integrated with in-house artificial thymic organoid systems, supporting structured adaptive immune development and functional human immune reconstitution without implantation of primary human thymic or other tissues. The platform is a BLT-equivalent system built entirely on commercially obtained cord blood derived cells.

No fetal tissue and no additional primary human tissues are used or offered within this system. All CD34-positive cells are sourced from FDA-registered tissue establishments that maintain donor eligibility documentation in accordance with 21 CFR Part 1271, and vendor documentation covers donor screening, infectious disease testing, traceability, and certificate of analysis. Vendors maintain institutional biosafety committee oversight for procurement and handling.

To discuss platform fit, study timelines, or immune monitoring requirements, request a quote.

Why thymic support matters

Conventional CD34-positive humanized models rely on the murine thymus to support human T-cell maturation. These systems have broad utility, but murine thymic stromal elements may limit aspects of human T-cell developmental programming and repertoire shaping, since the stromal signals a developing human thymocyte receives are not the ones it would encounter in a human thymus.

Artificial thymic organoid systems provide a structured three-dimensional microenvironment that recapitulates key stromal signaling cues required for T-cell differentiation. They support early T-lineage commitment, T-cell receptor rearrangement, CD4 and CD8 lineage specification, and controlled developmental staging. Integrating these systems into the CD34-positive humanized workflow allows structured T-cell developmental programming prior to or in coordination with in vivo engraftment, supporting adaptive immune modeling while avoiding implantation of primary thymic tissue entirely.

Platform architecture

The system consists of four stages: commercial procurement of cord blood derived CD34-positive cells, in-house artificial thymic organoid integration, in vivo engraftment into immunodeficient recipient mice, and tumor model establishment with therapeutic evaluation. Artificial thymic organoids are generated under controlled laboratory conditions, with quality controls covering cell viability assessment, surface marker validation, and developmental staging confirmation.

Reconstitution kinetics and study eligibility

Following engraftment, the first weeks are occupied by homing and establishment of the marrow niche. Human CD45-positive cells become detectable in peripheral blood thereafter, followed by expansion of T and B cell populations, with multilineage reconstitution stabilizing over subsequent months before study-eligible immune profiles are reached.

Study initiation requires peripheral human CD45-positive cells above a defined threshold, a detectable CD3-positive T-cell population, a balanced CD4 to CD8 distribution, and absence of clinical distress. Animals not meeting these criteria are excluded before randomization. Applying eligibility thresholds rather than enrolling all reconstituted animals is the principal means of controlling the donor-to-donor variability intrinsic to this class of model.

Applications

The platform is particularly relevant to immune checkpoint inhibitor evaluation, bispecific T-cell engager testing, CAR-T and T-cell receptor engineered cell persistence studies, cytokine biology and immune agonist evaluation, and combination immunotherapy optimization. Tumor configurations include subcutaneous xenografts, orthotopic models, metastatic dissemination models, and systemic hematologic malignancy models.

Endpoints and analytical capabilities

Primary endpoints are tumor volume, tumor growth inhibition, and survival. Secondary endpoints include flow cytometric immune profiling, cytokine quantification by ELISA and multiplex methods, and immunohistochemistry-based assessment of immune infiltration.

Immune profiling panels cover human CD45, CD3, CD4, CD8, CD19, CD56, CD14, and activation and checkpoint markers. Cytokine quantification covers interferon gamma, interleukin 2, tumor necrosis factor alpha, and interleukin 6. Immunohistochemistry quantifies CD8-positive infiltration, CD4-positive density, tumor architecture, and immune spatial distribution within the tumor.

Applied examples

Checkpoint inhibitor evaluation. Humanized mice bearing subcutaneous solid tumors are randomized to vehicle or anti-PD-1 therapy, with tumor volume and growth inhibition measured alongside CD8-positive infiltration and interferon gamma, linking tumor control to effector infiltration rather than reporting growth alone.

Bispecific antibody therapeutic index. A CD3-engaging bispecific is evaluated across a dose range, with tumor regression and cytokine elevation assessed in parallel to identify the dose balancing efficacy against cytokine-driven toxicity.

CAR-T persistence. A systemic leukemia model is treated with CAR-T cells across a dose range, with tumor clearance and persistence of the transferred product tracked through the study period to distinguish transient activity from durable engraftment.

Statistical framework and variability

Studies use predefined primary endpoints, randomization stratified by baseline tumor size, mixed effects modeling for tumor growth, Kaplan-Meier analysis for survival, and multiplicity control where applicable. Power calculations incorporate anticipated variance in immune reconstitution rather than assuming the uniformity of a conventional xenograft cohort.

Recognized sources of variability are donor-to-donor differences in immune reconstitution, tumor establishment variability, and heterogeneity in cytokine response. These are mitigated through eligibility thresholds, stratified randomization, controlled housing and monitoring, and defined sampling schedules.

Regulatory and compliance framework

All in vivo procedures are conducted under active institutional animal care and use committee protocols. For studies formally designated as GLP, Good Laboratory Practice standards are applied in accordance with applicable regulatory frameworks. CD34-positive cell vendors maintain institutional biosafety committee oversight for procurement and handling, and Altogen Labs maintains internal biosafety controls, traceability documentation, and quality assurance oversight consistent with regulatory expectations for preclinical programs intended to inform translational and IND-enabling development. No fetal tissue or additional primary human tissues are used or offered.

Send mechanism, tumor model, and study duration requirements, or request a quote.