Pepkio Confluency & Split Passage Planner

A Python interface for calculating cell culture split ratios, seeding densities, harvest yields, and passage schedules based on cell growth kinetics and vessel surface areas.

What It Does

Passaging adherent or suspension cell cultures requires calculating split ratios, seeding densities, total cell yields, and liquid transfer volumes. Manual rule-of-thumb split ratios (such as 1:3 or 1:5) fail to account for variations in current confluency, cell doubling kinetics, and vessel geometry, often causing inconsistent cell growth or weekend over-confluency.

This package provides programmatic access to the Pepkio cell passage planning engine. Researchers can input current vessel confluency, cell doubling time ($T_d$), target seeding density (cells/cm² or cells/mL), and vessel formats to calculate exact split ratios, harvest yields, transfer volumes, and passage timing.

Programmatic runs require a network connection and a Pepkio API key.

Features

• Adherent and Suspension Support: Computes surface-area seeding densities (cells/cm²) for adherent monolayers and concentration-based seeding (cells/mL) for suspension cultures.
• Standard Vessel Surface Area Database: Built-in surface areas and working volumes for 96-well through 6-well microplates, T-25, T-75, T-175, and T-225 flasks, and 60mm, 100mm, and 150mm dishes.
• Growth Kinetics Forecasting: Uses cell doubling time ($T_d$) to project cell accumulation kinetics and predict hours or days required to reach target harvest confluency.
• Multi-Mode Seeding Calculations: Computes subculturing parameters by target seeding density, target split ratio, or total cell count per vessel.
• Pipetting Reserve Allowance: Includes configurable safety overhead percentages (5% to 15%) to prevent liquid deficits during multi-vessel transfers.
• Programmatic & CLI Interfaces: Access via Python PepkioClient or the pepkio-confluency-split-passage-planner command-line tool.

Installation

pip install pepkio-confluency-split-passage-planner

Set an API key before invoking run():

export PEPKIO_API_KEY="your-api-key"

Quick Example

from pepkio_confluency_split_passage_planner import PepkioClient

with PepkioClient() as client:
    # Load example input for a standard HEK293 split in a T-75 flask
    inp = client.get_example_input("hek293_t75_split")
    result = client.run(inp)

    split = result.result["split"]
    print("Split Ratio:", split["split_ratio_label"])
    print("Harvest Total Cells:", f"{split['harvest_total_cells']:.2e}")
    print("Required Suspension Volume:", split["required_suspension_volume_ml"], "mL")
    print("Hours to 80% Confluency:", split["predicted_hours_to_80_percent_confluency"], "h")

CLI command:

pepkio-confluency-split-passage-planner run --example hek293_t75_split

Typical Use Cases

• Adherent Cell Subculturing: Determining exact split ratios and cell suspension transfer volumes to passage confluent culture flasks (e.g., HEK293, HeLa, CHO, NIH-3T3).
• Weekend Passage Scheduling: Calculating reduced seeding densities on Friday to ensure cultures reach 80% target confluency on Monday morning.
• Vessel Format Scale-Up: Translating seeding protocols across different culture vessel sizes (e.g., scaling from 6-well plates to T-75 or T-175 flasks) while maintaining constant density per unit surface area.
• Suspension Culture Maintenance: Calculating dilution ratios and fresh media volumes for suspension cell lines (e.g., Jurkat, K562, CHO-S) to remain within log-phase growth windows.
• Multi-Well Assay Seeding: Calculating master mix suspension volumes and cell counts required to seed 24-well or 96-well assay plates.

Scientific Background

Cell population growth during logarithmic phase follows first-order exponential kinetics:

$$N(t) = N_0 \cdot 2^{\frac{t}{T_d}}$$

where $N(t)$ is the cell population at time $t$, $N_0$ is the initial seeded population, and $T_d$ is the cell doubling time in hours. The incubation duration $t$ required to reach a target cell yield $N(t)$ is given by:

$$t = T_d \cdot \log_2 \left( \frac{N(t)}{N_0} \right)$$

For adherent cells, total harvest yield $N_{\text{harvest}}$ is derived from vessel surface area $A$ ($\text{cm}^2$), maximum monolayer cell density $D_{\text{max}}$ ($\text{cells/cm}^2$), and percentage confluency $C_{%}$:

$$N_{\text{harvest}} = D_{\text{max}} \cdot A \cdot \left( \frac{C_{%}}{100} \right)$$

The split ratio $R$ represents the proportion of harvested cells required to seed $m$ new target vessels at density $D_{\text{target}}$:

$$R = \frac{N_{\text{harvest}}}{m \cdot D_{\text{target}} \cdot A}$$

Pipetting reserve volume accounts for liquid hold-up during multi-vessel transfers by applying a safety overhead factor $P_{\text{reserve}}$ to the net transfer volume.

Web Application

For researchers who prefer a graphical interface, an interactive Confluency & Split Passage Planner is available in the browser.

The web interface offers interactive split visualizations, passage schedule timelines, plate layout summaries, and shareable permalinks.

Documentation and Resources

GitHub Repository: https://github.com/pepkio/pepkio-confluency-split-passage-planner

Web Application: https://www.pepkio.com/tools/confluency-split-passage-planner

About Pepkio

Pepkio (https://www.pepkio.com/) develops software tools and bioinformatics solutions for life science researchers, including laboratory calculators and analysis services (https://www.pepkio.com/cro).

Keywords

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A semantic, AI-native version of this document in the K2F format is available at https://k2f.dev (https://k2f.dev/v/a82d9704864e08d2f4f4d1ce029f690138c4c3d832afd844c100740fa7205918)