Hypotonic Citrate Buffer for Single-Cell hPSC Detachment
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Solution Overview
Problem
Current methods for passaging human pluripotent stem cells (hPSCs) face challenges in scalability, cell viability, and genetic stability, particularly when using enzymatic dissociation methods that can impact cellular characteristics and karyotypic integrity, and existing non-enzymatic methods like VERSENE® EDTA are not ideal for multilayer vessels, resulting in low yield and labor-intensive processes.
Innovation Solution
A formulation comprising 1 mM to 30 mM sodium citrate, 10 mM to 170 mM KCl or NaCl, and Ca2+/Mg2+-free Dulbecco's phosphate buffered saline (DPBS) with an osmolarity of 100 mOsmol/liter to 350 mOsmol/liter is used for harvesting and passaging hPSCs, allowing for high-yield single cell detachment without enzymes or mechanical scraping, maintaining pluripotency and karyotypic stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If enzymatic dissociation methods are used for passaging hPSCs, then cell detachment efficiency is improved, but cellular characteristics and karyotypic stability deteriorate
Solution Approach 1:
The patent replaces enzymatic dissociation (chemical system) with a mechanical/osmotic system using hypotonic buffer solution and physical agitation to achieve cell detachment, thereby avoiding the harmful effects of enzymes on cellular characteristics and karyotypic stability while maintaining detachment efficiency
Solution Approach 2:
The patent changes the osmolarity parameter of the buffer solution to hypotonic conditions (lower than physiological osmolarity), which causes cell swelling and facilitates detachment from culture vessels without requiring enzymes, thus preserving cell integrity and genetic stability
2Productivity
If mechanical scraping is used for cell detachment, then detachment efficiency is improved, but cell viability deteriorates
Solution Approach 1:
The patent replaces direct mechanical scraping with a gentler mechanical/osmotic system combining hypotonic buffer treatment and mild physical agitation, achieving effective detachment while minimizing mechanical damage to cells and maintaining high viability
Solution Approach 2:
The patent introduces a hypotonic buffer solution as an intermediary medium that facilitates cell detachment through osmotic pressure changes, reducing the need for direct mechanical contact and scraping that would otherwise damage cell membranes and reduce viability
3Ease of operation
If traditional flask-based passaging is used, then cell culture is simplified, but scalability deteriorates
Solution Approach 1:
The patent develops a universal passaging protocol using hypotonic buffer that can be applied across multiple culture formats including traditional flasks, multi-layer vessels, and microcarrier systems, enabling the same method to serve both simple and scalable culture needs
Solution Approach 2:
The patent segments the cell culture system into modular components that can be scaled independently, allowing the hypotonic buffer passaging method to be applied in various vessel types and configurations to meet different production scale requirements while maintaining operational simplicity
4Object-generated harmful factors
If VERSENE® EDTA is used for passaging, then non-enzymatic detachment is achieved, but yield and adaptability to multilayer vessels deteriorate
Solution Approach 1:
The patent changes the osmolarity parameter from isotonic (VERSENE® EDTA) to hypotonic conditions, which enhances cell detachment efficiency and yield while maintaining the non-enzymatic advantage, and the method proves adaptable to multilayer vessels where VERSENE® EDTA failed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The formulation enables high viability (>90%) and efficient passaging of hPSCs as single cells from various culture vessels, including 3D suspension cultures, with maintained pluripotency and differentiation capability, reducing labor intensity and minimizing genetic instability.
Implementation Method 1
The formulation comprises 1 mM to 30 mM sodium citrate
Implementation Method 2
said formulation has an osmolarity of about 100 mOsmol/liter to about 350 mOsmol/liter
Data Source
AI summary
The field of the invention is cellular and molecular biology and stem cells. Specifically, the disclosure is directed to a formulation for harvesting and passaging single cell human pluripotent stem cells comprising: (i) 1 mM to about 30 mM sodium citrate; (ii) a salt comprising 10 mM to 170 mM KCl or NaCl; and (iii) Ca2+/Mg2+-free Dulbecco's phosphate buffered saline (DPBS), wherein said formulation has an osmolarity of about 100 mOsmol/liter to about 350 mOsmol/liter. The formulation can be used for serial passaging and dislodging of pluripotent stem cells attached to 2D tissue culture vessels or grown in 3D suspension culture (small scale and large scale bioreactors) or any other application where passaging in the form of single cell population of stem cells is needed.