Meniscus Graft Vitrification With Model-Based CPA Loading
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Solution Overview
Problem
Existing cryopreservation methods for avascular tissues like knee menisci and TMJ discs result in significant cell damage due to ice crystal formation, leading to a shortage of viable grafts for transplantation and unsatisfactory clinical outcomes.
Innovation Solution
A system utilizing computational modeling and microcomputed tomography (μCT) imaging to optimize cryoprotectant agent (CPA) distribution and minimize exposure time, transitioning tissues into a vitreous state to prevent ice crystal formation, ensuring adequate penetration and reducing cell toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional slow-freezing cryopreservation is used, then ice crystal formation occurs during freezing and recrystallization, but this causes significant cell damage and loss of cell viability
Solution Approach 1:
The patent applies vitrification, a phase transition process where the tissue-CPA mixture transitions directly from liquid to glassy solid state without forming ice crystals. By controlling the phase transition through rapid cooling and CPA concentration, the invention eliminates ice crystal formation that causes cell damage in traditional freezing methods
Solution Approach 2:
The invention changes key parameters including CPA concentration (using high concentrations like 55% VS55), cooling rate (rapid cooling to achieve vitrification), and temperature thresholds (cooling below glass transition temperature Tg). These parameter changes prevent ice crystal formation while maintaining cell viability
2Object-affected harmful factors
If high concentrations of cryoprotectant agents are used to protect from ice crystal damage, then cell toxicity increases during prolonged exposure
Solution Approach 1:
The patent uses rapid cooling to skip through the ice crystal formation temperature range and achieve vitrification quickly. This rushing through the dangerous temperature zone minimizes the time cells are exposed to high CPA concentrations, reducing toxicity while still achieving protection from ice crystal damage
Solution Approach 2:
The invention performs preliminary CPA loading to achieve adequate penetration before vitrification, using computational modeling to optimize the loading time. This preliminary action ensures sufficient CPA concentration is achieved without excessive exposure time that would cause toxicity
3Quantity of substance
If extended CPA exposure is used for dense avascular meniscus tissues to achieve adequate penetration, then CPA exposure time increases causing cytotoxicity
Solution Approach 1:
The patent performs preliminary CPA loading with optimized duration based on computational modeling predictions. The model determines the exact time needed for adequate CPA penetration into the dense meniscus tissue, allowing the process to stop at the optimal point rather than using extended exposure times that would cause toxicity
Solution Approach 2:
The invention uses computational modeling to provide feedback on CPA distribution and penetration depth in real-time during the loading process. This feedback mechanism allows dynamic adjustment of loading time to achieve adequate penetration while minimizing exposure time and associated toxicity
4Volume of stationary object
If vitrification is used for larger tissues greater than 3 ml, then CPA penetration becomes challenging and success is hindered
Solution Approach 1:
The patent performs preliminary CPA loading with extended but optimized duration for large tissues, using computational modeling to determine the exact time needed for adequate penetration throughout the entire volume. This preliminary action ensures sufficient CPA distribution before vitrification without using excessive time that would cause toxicity
Solution Approach 2:
The invention uses computational modeling to provide feedback on CPA penetration progress in large tissues, allowing dynamic adjustment of loading parameters to ensure adequate penetration throughout the entire tissue volume while minimizing exposure time
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 system achieves high cell viability and maintains the extracellular matrix structure and biomechanical strength of vitreous grafts, with viability rates exceeding 70% and improved metabolic activity, outperforming traditional slow-freezing methods.
Implementation Method 1
transitioning tissues into a vitreous state to prevent ice crystal formation
Implementation Method 2
A cryopreservation process is provided
Implementation Method 3
optimize cryoprotectant agent (CPA) distribution
Data Source
AI summary
A system and m ethos for vitrification by transitioning tissues into a vitreous state at cryogenic temperatures and protecting them from ice crystal damage using high concentrations of cryoprotectant agents (CPAs). This system balances penetration and reducing cell toxicity. The system and method use a simulation-based optimization approach developed by combining computational modeling with microcomputed tomography imaging to predict three-dimensional CPA distributions within tissues over time accurately. In one embodiment, CPA exposure time was minimized, resulting in 85% viability in 4-ml meniscal specimens, 70% in 10-ml whole knee menisci, and 85% in 15-ml whole TMJ menisci (i.e., TMJ disc) post-vitrification, outperforming slow-freezing methods (20%-40%). Vitreous meniscus grafts demonstrated clinical-level viability (≥70%), closely resembling the material properties of native tissues, with long-term availability for transplantation.