122. Procurement and Preservation by Ex Vivo Perfusion of Porcine Hindlimbs for Vascularized Composite Allotransplantation
Bibliographic record
Abstract
PURPOSE: Vascularized composite allotransplantaion (VCA) is an emerging reconstructive technique for treating significant soft tissue and skeletal defects presenting functional deficiencies. At present, limb transplant is severely limited by irreversible ischemic damage of highly metabolic skeletal muscle tissue after 3-4 hours, and is highly susceptible to ischemia-reperfusion injury (IRI). To increase clinical feasibility and success of VCA, new preservation techniques are required to prolong storage time before transplantation. The purpose is three-fold: (1) to bridge the translational gap from rodent to human with a new porcine model; (2) to engineer an ex-vivo limb perfusion system; and (3) test various perfusates to find optimal preservation conditions. Prolongation of storage will increase limb transplant accessibility and advance VCA reconstruction. METHODS: Porcine hindlimbs are procured from cadaveric Yorkshire pigs by incising along the inguinal ligament and dissecting down to the femoral vessels and lateral circumflex femoral vessels. Once the femoral pedicle is visualized, lateral circumflex femoral vessels are ligated, soft tissue is circumferentially dissected around the hip joint, the femoral head is dislocated, and the femoral vessels are ligated and cannulated. Control hindlimbs are placed in static cold storage (SCS). Experimental hindlimbs are perfused via a custom closed-circuit bioreactor containing a pulsatile pressure pump, perfusate reservoir, oxygenator, carbogen gas (95% O2, 5% CO2), and a pressure monitor. Limbs are perfused at 300 mL/min. with target physiologic pressure of 80 mmHg. Arterial inflow and arterial outflow are sampled, as well as all tissue components including skin, nerves, muscle, bone and vessel are biopsied at regular intervals for histological assessment of cell structure and death, adequate oxygen delivery, and metabolic changes. RESULTS: Development of the pig hindlimb surgical procurement has yielded a new research model for VCA research extending beyond rodent and forelimb models. The limb retains intact muscle, bone, vasculature, and nerves and vessels are successfully ligated creating the start and end of the closed circuit loop at the femoral artery and vein respectively. Preliminary ex vivo perfusion bioreactor and circuit can carry out perfusion with successful venous outflow. CONCLUSION: The development of surgical porcine hindlimb procurement successfully produced a viable and novel model for studying VCA preservation prolongation and IRI. The successful bioreactor and ex vivo perfusion circuit design serves as a tool to examine different perfusates against an SCS control. Next steps include developing perfusate cocktails for experimental condition with aim to prolong preservation of the porcine hindlimb and analysis for reduction of irreversible ischemia.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".