🛰️ PulseGrowth | Host Cell Lab Suite

Growth kinetics and process timing. Fast, clear, and lab-ready.

PulseGrowth is a lightweight web app for analyzing cell growth kinetics and estimating process timing in mammalian cell culture workflows.
It is part of Host Cell, a growing suite of practical laboratory and bioprocess tools built by Emiliano Balderas (IBt-UNAM).

Repo • Live App

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What is PulseGrowth?

PulseGrowth helps convert routine sampling data into actionable bioprocess metrics for mammalian cell culture.

The app is organized into three practical modules:

• Bio-Kinetics: calculates growth metrics from two sampling points
• Metabolics (q): estimates qGlc and qGln normalized by IVCD
• Feed Control: estimates simple feed additions to restore target concentrations

It is designed for quick bench-side calculations, passaging decisions, and culture monitoring.

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🧬 Scientific Fundamentals

PulseGrowth uses an exponential growth model between two sampling points:

$$X = X_0 \cdot e^{\mu t}$$

Variable definitions

• X0: initial viable cell density (typically in ×10⁶ cell/mL)
• X1: final viable cell density (typically in ×10⁶ cell/mL)
• Δt: elapsed time between measurements
• μ: specific growth rate

Core growth calculations

PulseGrowth calculates:

$$\mu = \frac{\ln(X_1/X_0)}{\Delta t}$$

$$t_d = \frac{\ln(2)}{\mu}$$

$$\text{Expansion factor} = \frac{X_1}{X_0}$$

IVCD (exponential approximation)

To normalize metabolite consumption rates, PulseGrowth estimates Integrated Viable Cell Density (IVCD) as:

$$IVCD = \left(\frac{X_1 - X_0}{\ln(X_1/X_0)}\right)\Delta t$$

This is useful for obtaining more comparable specific rates (q) than using only initial or final cell density.

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✅ Calculation Logic (How PulseGrowth computes results)

This section explains exactly how the app performs the calculations.

1) Bio-Kinetics module

Given X0, X1, and Δt:

1. Convert Δt to a common internal time basis (hours, if needed)
2. Compute μ using the exponential growth equation
3. Compute doubling time from μ
4. Compute expansion factor = X1/X0
5. Compute IVCD for downstream q calculations

2) Metabolics module (qGlc / qGln)

PulseGrowth estimates specific metabolite rates using concentration change normalized by IVCD.

Step A: Normalize concentration units

If the user enters metabolite concentrations in g/L, the app converts them internally to mM using molecular weight (MW):

$$mM = \frac{g/L}{MW\ (g/mol)} \times 1000$$

Default MW values used:

• Glucose (Glc) = 180.156 g/mol
• Glutamine (Gln) = 146.145 g/mol

If the user enters values directly in mM, no conversion is needed.

Step B: Compute concentration change

For each metabolite:

$$\Delta C = C_0 - C_1$$

Where:

• C0 = initial concentration
• C1 = final concentration

Positive ΔC means net consumption.

Step C: Compute specific rate (q)

PulseGrowth reports q values consistently in pmol/cell/day:

$$q = \left(\frac{\Delta C}{IVCD}\right)\times 24$$

Where:

• ΔC is in mM
• IVCD is in (10^6\ cell\cdot h)/mL
• The factor 24 converts from per-hour to per-day basis

3) Feed Control module (simple correction estimate)

PulseGrowth estimates the feed volume required to adjust a metabolite concentration from current to target level using a single-addition correction formula.

For a feed stock concentration Cstock, current concentration Ccurrent, target concentration Ctarget, and culture volume Vculture:

$$V_{feed} = \frac{(C_{target}-C_{current})V_{culture}}{C_{stock}-C_{target}}$$

This is a simple algebraic planner for practical lab use, not a full dynamic feeding model.

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✅ Unit Logic (Important)

PulseGrowth uses a unit strategy designed for consistency and comparability.

Cell density inputs

• Expected in ×10⁶ cell/mL

Time inputs

• hours or days
• Internally normalized for growth-rate calculations

Metabolite concentration inputs

• g/L or mM (for Glc / Gln)

q outputs

• Primary output: pmol/cell/day
• Optional display: pg/cell/day (mass-equivalent reference)

Correct use rule

PulseGrowth ensures q outputs are comparable by converting g/L → mM internally before calculation.

✅ This means:

• entering glucose as 6 → 4 g/L
• or entering equivalent values in mM

...will produce comparable qGlc values (aside from rounding), because the app normalizes units before computing q.

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⚡ Features

• Growth Kinetics Solver: Calculates μ, doubling time, and expansion factor
• IVCD-Based q Estimation: qGlc / qGln normalized using exponential IVCD approximation
• Unit-Aware Metabolite Inputs: Accepts g/L or mM and converts internally
• Simple Feed Planner: Quick feed-volume estimates for glucose and glutamine correction
• Time Input Flexibility: Manual Δt or start/end datetime input
• Mobile-First UI: High-contrast, telemetry-inspired interface for real lab use
• PWA Ready: Installable on Android/iOS and usable offline after first load
• Host Cell Design System: Visual consistency with other tools in the suite

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🔬 Typical Use Cases

PulseGrowth is useful for:

• estimating whether a culture is still in exponential growth
• comparing growth performance across clones or conditions
• calculating doubling time for passaging planning
• estimating qGlc and qGln from routine sampling data
• planning simple corrective feeds for glucose/glutamine
• reducing manual calculator/transcription errors during culture operations

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🚀 How to Use

Bio-Kinetics

1. Enter X0, X1, and Δt
2. Select time unit (h or day)
3. Click Analyze kinetics
4. Review μ, t_d, expansion factor, and IVCD

Metabolics (q)

1. Enter Glc and/or Gln concentrations as C0 → C1
2. Select units (g/L or mM)
3. Click Calculate q
4. Review qGlc and qGln in pmol/cell/day

Feed Control

1. Enter culture volume
2. Enter stock concentrations and target concentrations
3. Click Calculate feed plan
4. Review estimated feed volumes

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📱 Installation (PWA)

PulseGrowth can be installed as a Progressive Web App (PWA) for faster access and offline use.

Android / Desktop (Chrome, Edge)

• Open the live app
• Tap/click Install App (if shown)
• Or use the browser install prompt/menu

iPhone / iPad (Safari)

• Open the live app
• Tap Share
• Select Add to Home Screen

Once installed, the app can work offline after the required files are cached.

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❓ FAQ

Q: Why does PulseGrowth convert g/L to mM for q calculations?
A: Because q should be comparable across inputs. Concentration changes in g/L and mM are not directly equivalent without using molecular weight (MW). PulseGrowth converts to mM internally before computing q.

Q: What does a positive q mean?
A: By convention in PulseGrowth, q > 0 means net consumption (C0 > C1). Negative q means the metabolite increased over time (net accumulation/production).

Q: Is IVCD exact?
A: No. The app uses an exponential approximation of IVCD between two sampling points. It is practical and useful for routine comparisons, but still depends on the underlying growth behavior and data quality.

Q: Does this replace process models or SOPs?
A: No. PulseGrowth is a calculation aid for rapid workflow support. Always validate decisions against SOPs, process knowledge, and experimental context.

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⚠️ Notes and Limitations

• PulseGrowth is a calculation aid, not a substitute for SOPs or experimental judgment.
• Exponential assumptions may not hold if the culture is in lag/stationary/decline phase.
• IVCD is an approximation based on two sampling points.
• Feed calculations are simplified and intended for quick operational estimates.
• Always verify:
  • units and concentration basis
  • sampling times
  • viable cell count quality / counting consistency
  • stock solution identity and concentration
• For critical workflows, follow institutional protocols and lab-specific validation practices.

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👨‍🔬 Author

Emiliano Balderas
Biotechnology Engineer | PhD Student in Biochemistry
Instituto de Biotecnología (IBt) - UNAM

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🧩 About Host Cell

Host Cell is a growing suite of practical lab and bioprocess tools focused on:

• clarity
• speed
• reproducibility
• real-world usability at the bench

PulseGrowth is one module in that ecosystem.

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Host Cell Lab Suite – Practical tools for high-performance biotechnology.