A research study in which bioengineered tissue derived from pigs was implanted into the eyes of 14 humans with visual impairments resulted in “final mean best-corrected vision,” and “restored tolerance to contact lens wear,” for patients, according to researchers.
Study results were published Thursday in the Nature journal.
Researchers sought to develop a material to help millions worldwide who have visual impairment related to corneal stroma diseases such as keratoconus (thinning and bulging of the cornea). The cornea is a transparent part of the eye that covers the iris and the pupil and allows light to enter the eye. Corneal stroma is the thickest layer of the cornea and it plays an important role in vision.
To create a “collagen-based corneal stromal substitute,” scientists purchased medical-grade purified freeze-dried type I porcine [pig] dermal atelocollagen from SE Eng Company in South Korea. This was used to manufacture “BPCDX” at a facility in Linköping, Sweden by LinkoCare Life Sciences AB.
Previously, other researchers found that “the histologic structure of porcine-derived collagen is similar to that of human dermal collagen.”
According to authors of the recent study, “standard penetrating corneal transplantation surgery” for keratoconus uses human donor corneas. This method has complications, including securing consent for donation, harvesting corneas postmortem, pathogen testing and short-term storage in accredited facilities.
“Bioengineering implantable tissue is the key to addressing the global burden of corneal blindness,” though it hasn’t been featured in many human studies, the researchers explained.
For example, they expect that BPCDX could be widely distributed and stored up to two years. It can also be stored at room temperature or in a refrigerator and since it is packaged and sterile, it does not require pathogen testing needed for human tissue, “thus representing a safer alternative in times of viral outbreaks.”
Use of medical grade and FDA-approved dermal collagen sourced from pigs, which has “ultra-purity” allows for the production of a “more mechanically robust hydrogel” that can be consistent batch-to-batch.
“No other technology has achieved manufacturability, packaging, sterility and long shelf life that are ISO-compliant and independently third-party certified,” said the study. “Yet these often-overlooked aspects are critical for addressing the global lack of donor cornea tissue in practical terms.”
In addition to potentially being easier to make, distribute and store, researchers said “visual gains we report,” with BPCDX represent equivocal outcomes to human corneal transplants.
For the study, researchers implanted BPCDX in 20 advanced keratoconus subjects in Iran and India “to reshape the native corneal stroma without removing existing tissue or using sutures,” and observed no adverse events during a two-year follow up.
To implant BPCDX, researchers adapted an intrastromal procedure that had not previously been described in human patients, to their knowledge. They said they were able to flatten corneas more than would be possible with human donor corneas and that the procedure does not require extensive training.
People with keratoconus may find it difficult to wear contact lenses as a means of vision improvement due to the cone shape of their cornea. Flattening the cornea can help, and in the case of the recent study, 100% of participants were able to tolerate contacts after their operation.
“Our surgical approach achieved an unprecedented central corneal thickness increase ten times that of previous studies sustained for at least 2 years, resulting in three times the degree of corneal flattening of previous studies and a substantially greater improvement in vision,” said the study.
Researchers expect the gains to be stable, and to possibly exceed results from procedures that utilize human donor material.
“Future clinical studies will be needed to test this assertion,” they said.
Reported results from the study have been submitted to regulators. Another clinical trial of BPCDX and the intrastromal procedure described by study authors as a treatment for presbyopia has been granted regulatory approval in the European Union.
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