The journal Nature Biotechnology published exciting news of a bioengineered implant used in place of corneal transplants for treatment of advanced keratoconus. 

     For more than a decade, biomedical engineers at Linkoping University in Sweden have been refining a replacement for human cornea tissue.  They note that 12.7 million people worldwide have cornea-related blindness that could be improved with a corneal transplant, and yet the current supply is one donor cornea for every 70 needed.  Most of the supply of available corneas are found in a handful of countries.  Many lower- and middle-income countries have limited or no eye banking facilities, and a lack of trained personnel for tissue harvesting and preparation.

      The bioengineered tissue starts as collagen collected from pigskin.  The collagen is tested, treated, and undergoes two separate crosslinking procedures to stiffen the tissue.  The result,  BPCDX (bioengineered porcine construct double crosslinked), is biocompatible and contains no cells, stiff enough to flatten the curve of a cornea, does not degrade, and can be easily produced and packaged. The single best feature may be that BPCDX has a shelf life of 2 years compared to human donor tissue which must be used within 2 weeks.  The authors are confident BPCDX will improve availability and reduce storage problems that exist in countries where performing corneal transplants is rare.

     The paper described 10 patients in Iran and 10 in India, blind or nearly blind as a result of advanced keratoconus, recruited for the pilot study.  Both countries have high rates of keratoconus (2.3% of India’s population or 30 million people, and 4% or 3.4 million in Iran).  All subjects were contact lens intolerant and had extremely steep and thin corneas due to advanced disease.  A simple incision was made into the cornea, creating a pocket, and the BPCDX was slipped into place with no stitches required to close the wound.   

      After two years of observation, the corneas remain clear, and no scarring developed.  All patients experienced improved vision, flattening of their cornea, and were able to wear contact lenses.   

     The next step will be a large-scale clinical trial comparing long-term results with BPCDX to those with traditional corneal transplant.  For countries where human donor tissue is scarce, the availability of bioengineered tissue like BPCDX may offer those with advanced keratoconus a second chance at sight. 

Reference:  Rafat M, Jabbarvand M, Sharma N, et al, Bioengineered corneal tissue for minimally invasive vision restoration in advanced keratoconus in two clinical cohorts, Nat Biotechnol. 2022 Aug 11. doi: 10.1038/s41587-022-01408-w. Online ahead of print. PMID: 35953672