Modernizing Storage Conditions for Fresh Osteochondral Allografts by Optimizing Viability at Physiologic Temperatures and Conditions

Abstract

Objective. Osteochondral allograft (OCA) transplantation has demonstrated good long-term outcomes in treatment of cartilage defects. Viability, a key factor in clinical success, decreases with peri-implantation storage at 4°C during pathogen testing, matching logistics, and transportation. Modern, physiologic storage conditions may improve viability and enhance outcomes. Design. Osteochondral specimens from total knee arthroplasty patients (6 males, 5 females, age 56.4 ± 2.2 years) were stored in media and incubated at normoxia (21% O2) at 22°C or 37°C, and hypoxia (2% O2) at 37°C. Histology, live-dead staining, and quantitative polymerase chain reaction (qPCR) was performed 24 hours after harvest and following 7 days of incubation. Tissue architecture, cell viability, and gene expression were analyzed. Results. No significant viability or gene expression deterioration of cartilage was observed 1-week postincubation at 37°C, with or without hypoxia. Baseline viable cell density (VCD) was 94.0% ± 2.7% at day 1. At day 7, VCD was 95.1% (37°C) with normoxic storage and 92.2% (37°C) with hypoxic storage ( P ≥ 0.27). Day 7 VCD (22°C) incubation was significantly lower than both the baseline and 37°C storage values (65.6%; P < 0.01). COL1A1, COL1A2, and ACAN qPCR expression was unchanged from baseline ( P < 0.05) for all storage conditions at day 7, while CD163 expression, indicative of inflammatory macrophages and monocytes, was significantly lower in the 37°C groups ( P < 0.01). Conclusion. Physiologic storage at 37°C demonstrates improved chondrocyte viability and metabolism, and maintained collagen expression compared with storage at 22°C. These novel findings guide development of a method to optimize short-term fresh OCA storage, which may lead to improved clinical results.

Fresh Osteochondral and Chondral Allograft Preservation and Storage Media: A Systematic Review of the Literature

“…The control media or standard storage solution for OCAs varied among studies (eg, Dulbecco’s modified Eagle medium [DMEM], minimum essential medium Eagle [MEME], DMEM/F-12) and included different supplements: serum and/or various amino acids, buffers, and vitamins. 17,24,30,42,47,69 However, other types of storage solutions have been investigated, such as the University of Wisconsin Solution, Euro-Collins solution, chondrogenic media, lactated Ringer solution, and Missouri Osteochondral Allograft Preservation System. A number of studies reported no improvement or inferior storage outcomes with lactated Ringer solution as compared with standard media.…”

“… # References 1-3, 5-7, 10, 15, 17-19, 24, 28-30, 37, 38, 42, 45, 47, 48, 53-55, 59-61, 63, 65, 69-76, 78-80. …”

No Difference in Outcomes Following Osteochondral Allograft with Fresh Precut Cores Compared to Hemi-Condylar Allografts

“…Recent studies have sought to optimize the storage of OCA grafts, to have a longer shelf life and higher cell count for viability, which may lead to improved cartilage quality in the implanted graft. 30,31 Beyond this, there are differences in storage and preparation between the fresh precut OCA cores and condylar OCA, which could impact outcomes and cell viability. However, despite our study showing no difference in the early radiologic outcomes, further optimization is still of great interest.…”

Variability in the Processing of Fresh Osteochondral Allografts

“…In accordance with standard tissue bank practice, all companies studied, with the exception of MTF, maintain grafts in temperatures between 1 and 10°C. 47,50 Many banks store grafts in a refrigerated environment due to concerns regarding infection if stored at higher temperatures. 4 However, according to a study by Pallante et al, preservation of fresh osteochondral allografts at 4°C leads to a significant reduction in the viability of the cartilage by 28 days.…”

“…To improve chondrocyte viability and graft success, additional research on optimal temperature is indicated and may guide future federal recommendations. 4,15,50,51…”