Recording of the 2025 ECTS–IFMRS Joint Session, Vienna
Speaker: Prof. Liesbet Geris (University of Liège & KU Leuven, Belgium)
Digital twins are no longer just an engineering curiosity; they are becoming a cornerstone of personalized medicine. In this keynote, delivered at the 2025 ECTS–IFMRS meeting in Vienna, Prof. Liesbet Geris demonstrates how patient-specific models are already guiding implant design and surgical planning, and then looks ahead to Europe’s ambitious ‘Virtual Human Twin’ platform, which will connect multiscale models, data, and standards across the continent.
Key Insights:
Data and model always go together
Digital twins rely on four layers working in concert:
sensors/measurements → middleware → computing hardware → software models.
Twins can represent cells, tissues, organs, whole systems, medical devices, bioprocesses or entire facilities, whichever is sufficient to answer the clinical or research question.
Modelling spans a spectrum, not just AI
From black-box, data-only approaches to white-box, physics-only ones, most useful twins sit in the grey zone – hybrid models that combine mechanistic knowledge with machine-learning components to curb ‘hallucinations’.
Lab examples show the breadth of scales
- Single-cell cartilage atlas & executable GRN model – maps chondrogenic differentiation states, then predicts interventions to steer cells; predictions validated in vitro.
- Multiscale osteoarthritis twin – links gait-derived joint loading → cartilage stress → integrin signalling → intracellular response.
- Curvature-driven scaffold growth model – converts the biological rule ‘cells fill concave corners first’ into maths; guided design of gyroid bone implants that outperformed lattices in mouse and large-animal studies.
- Agent-based fracture-healing model – simulates macrophage M0 → M1 → M2 dynamics and cytokine fields during the inflammatory phase; calibrated with in-vivo immunofluorescence, now being extended with mechanical loading data.
Clinical traction is already real (at single-organ scale)
Personalized left-atrial appendage occluder sizing, surgical planning tools, and other device-focused twins are in routine use and even reimbursed; one physics-only twin has entirely replaced a medical-device clinical trial.
Regulatory and credibility science are maturing
EMA/FDA guidance, emerging “Good Simulation Practice” and ~150 existing standards give clear (if complex) pathways for validation, documentation, and risk management.
Europe’s next step: the Virtual Human Twin initiative
The EU aims to knit dispersed efforts into a shared platform that includes:
- catalogue of models, data sets, and workflows;
- tooling for automated credibility tests;
- common metadata so models can ‘crawl’ data spaces;
- alignment with the European Health Data Space, AI Act, MDR, etc.
Community-built roadmap & manifesto
800+ stakeholders co-authored a 30-recommendation roadmap (plus a short policy brief and 2-page manifesto) emphasising unmet-need-driven use cases, full clinical-workflow integration, and sustainable infrastructure and business models.
Validation remains context-dependent
High-TRL scaffold work moves quickly from mouse to large-animal to spin-off products; the inflammatory fracture-healing twin is lower-TRL and still in fundamental calibration, illustrating that digital first, then bench & animal is iterative, not linear.
Bottom line
Digital twins are already delivering niche clinical value, and hybrid, multiscale approaches are unlocking far richer questions – from single-cell fate decisions to hospital logistics. Europe’s Virtual Human Twin push seeks to make those scattered successes reproducible, interoperable, and trustworthy at continent scale.
