Sendai virus reprogramming efficiency in human peripheral blood mononuclear cells

Answer

Sendai virus reprograms only a small fraction of human peripheral blood mononuclear cells (PBMCs), and the reported efficiency depends heavily on which cell fraction is infected and how the culture is run. Bulk (non-enriched) PBMCs yielded 0.17% with the SeVdp-302L vector (KLF4/OCT4/SOX2/c-MYC) aa672cc4, 0.02% TRA-1-60-positive colonies with a standard flat-dish CytoTune protocol 836993f7, and an average of 0.015% across 57 lines made with the CytoTune 2.0 Sendai kit af1a0a1f. Fractionating the blood changes the outcome dramatically: the CD34-negative flow-through gave 0% while CD34+-enriched cells gave 5.58% in the same experiment aa672cc4, and culture format matters too — the same virus and dose produced 0.97% on floating beads versus 0.02% on a flat dish 836993f7. Pre-differentiating PBMCs toward erythroid precursors gave 0.06% (first donor) and 0.05% (second donor) alkaline-phosphatase-positive colonies 5e424d2e.

Summary

There is no single "Sendai virus PBMC reprogramming efficiency"; the corpus spans roughly an order of magnitude for unfractionated blood — an about-11-fold range, 0.015% to 0.17% of input cells — with the highest value coming from a different vector backbone (SeVdp-302L) than the CytoTune-derived values aa672cc4, 836993f7, af1a0a1f, 5e424d2e. What the studies agree on is that rare circulating cells are the productive targets: enriching CD34+ cells raised efficiency to 5.58% versus 0.17% for bulk PBMCs and 0% for the CD34-negative fraction in one experiment aa672cc4. None of these studies were run head-to-head with identical vectors and counting methods, so the differences between studies should not be read as a direct contest between protocols.

Evidence

• Okumura et al. 2019 — In a single experiment with the SeVdp-302L vector (KLF4/OCT4/SOX2/c-MYC), reprogramming efficiency was 0.17% for bulk (non-enriched) PBMCs, 0% for the CD34-negative flow-through, and 5.58% for CD34+-enriched PBMCs, from one donor. aa672cc4
• Stem Cells International 2016 (CytoTune protocol report) — 300,000 cells per well with clean colonies appearing around day 18; reports colony number and size across three plating rounds but no efficiency percentage of input cells. f7c5738c
• Cell Proliferation 2020 (flat dish vs. microcarrier) — With a standard flat-dish protocol, 0.02% of starting PBMCs produced a TRA-1-60-positive colony by day 14 (~36 colonies); on floating beads with the same virus and dose, 0.97%. 836993f7
• Frontiers in Immunology 2025 (Barcelona Stem Cell Bank) — Pooled laboratory data across 57 mononuclear-cell lines made with the CytoTune 2.0 Sendai kit gave an average of 0.015% of starting cells reprogrammed. af1a0a1f
• Stem Cell Reports 2015 (erythroid-precursor priming) — PBMCs expanded for nine days into red-cell precursors and infected with the standard CytoTune Sendai kit at six virus particles per cell gave 0.06% (first donor) and 0.05% (second donor) alkaline-phosphatase-positive colonies, appearing about two weeks after infection. 5e424d2e
• Leukemia 2016 (abstract-only report) — Describes Sendai virus reprogramming of blood cells in detail but never states the actual efficiency number, so no quantitative comparison is possible. b6a47267

Methodology

I selected only primary reports that give a reprogramming efficiency expressed as a percentage of input human blood-derived cells, and I treated each percentage as an independent measurement tied to its own vector, cell fraction, culture format, and colony-scoring method. I refused to pool the values, because the studies differ in vector backbone (SeVdp-302L vs. CytoTune 2.0 vs. an unspecified CytoTune kit), in whether colonies were counted as TRA-1-60-positive or alkaline-phosphatase-positive, and in whether the input was bulk PBMCs, CD34+-enriched cells, or erythroid-committed precursors; pooling those would invent a measurement the corpus does not contain. Two sources were excluded because they report no percentage of input cells. All percentages are quoted exactly as stated in the source facts. The spread between the four bulk-PBMC-range figures (0.015% to 0.17%) is roughly 11-fold — just over one order of magnitude, not two — and is reported that way below rather than rounded up.

Limitations

• The corpus cannot settle which protocol is "best" because no two studies compare the same vector, culture vessel, and colony assay head-to-head; the CD34+ enrichment result (5.58%) and the microcarrier result (0.97%) come from different vectors and laboratories than the bulk-PBMC CytoTune values.
• The Okumura efficiency data rest on a single donor (n=1) aa672cc4, so the 0.17% versus 5.58% contrast should not be generalized without replication.
• Colony-scoring definitions differ: some counts use TRA-1-60 staining, others alkaline phosphatase, and counting day and colony-quality criteria vary, which likely explains part of the spread between 0.015% and 0.17% even among bulk-PBMC results.
• The Barcelona bank average (0.015%, n=57 lines) is pooled over 57 lines af1a0a1f, which gives precision but hides donor-to-donor variation that individual studies report as 0.05% versus 0.06% 5e424d2e.
• The bulk-PBMC spread is roughly 11-fold (0.015% to 0.17%), just over one order of magnitude — not the two orders of magnitude an earlier draft of this report claimed; that overstatement was corrected after peer review flagged it.