Biosynthetic corneas restore sight in patients with significant vision loss

Biosynthetic corneas restore sight in patients with significant vision loss

Patients with corneal damage and considerable vision loss had biosynthetic corneas implanted into their eyes with FibroGen's proprietary rhCIII (recombinant human type III collagen), which restored their vision and promoted nerve regeneration. A report on this 2-year Phase I clinical trial has been published in the peer-reviewed journal Science Translational Medicine.

The authors explain that damage to the cornea and corneal disease are major causes of blindness globally. Some countries have cornea tissue banks - corneas are collected from human donors. However, there is never enough human donor tissue to meet demand.

Even those lucky enough to receive a donor human cornea run the risk of complications, such as rejection - the body treats the new cornea as a foreign body and its immune system attacks and destroys it as it would a harmful bacterium or virus.

In some limited cases corneal prostheses (made from synthetic plastics) are used when human donor grafts cannot be used, or when they have not been successful. Even so, they do not promote tissue regeneration and do not replace donor tissues, the authors write.

FibroGen, pioneers of rhCII, collaborated with Dr. May Griffith of Linköping University, Sweden, and team to develop a biosynthetic molded from chemically cross-linked rhCIII. The biosynthetic implant mimics the human cornea, most of which consists of collagen (a protein).

Dr. Griffith, senior author of the report, said:

Recombinant human collagen is a viable replacement for naturally occurring human collagen that does not have the limitations of human donor tissue or animal-sourced collagens, such as risk of disease transmission and availability of donor supply. Our study provides proof-of-concept that corneal implants composed of recombinant human collagen can promote tissue regrowth and restore vision.

Thomas B. Neff, Chief Executive Officer of FibroGen, said:

These clinical results suggest that our collagen could potentially provide an important option for patients by reducing risk of disease transmission and increasing supply of corneal implant material in the face of the worldwide shortage of human donor corneas. This product concept continues to be improved and additional studies are planned.

In this Phase I clinical study 10 patients with corneal damage/disease underwent corneal resection (corneas surgically taken out), and then had the rhCIII-based biosynthetic corneas implanted.

Follow-ups two years after the surgical procedures took place, the researchers report that ALL of the transplanted corneas remain viable, cells from the patients' own corneas had grown into the implant. Nerves that had been severed during surgery were restored. Blink reflex and tear film were also restored, the scientists wrote.

After two years, best spectacle-corrected visual acuity:

  • Improved in six patients
  • Stayed the same in two patients
  • Decreased in two patients
The medical team reported no cases of rejection reaction. None of the patients required long-term immunosuppressive therapy (medications to stop the body from rejecting the implant).

The authors concluded:

With further optimization, biosynthetic corneal implants could offer a safe and effective alternative to the implantation of human tissue to help address the current donor cornea shortage.

FibroGen Inc. informs that 10 million people worldwide have vision loss caused by corneal disease or damage. The serious shortage of good quality donor tissue leaves a significant proportion of these patients with long-term vision loss.

Source: FibroGen Inc., Science Translational Medicine

"A Biosynthetic Alternative to Human Donor Tissue for Inducing Corneal Regeneration: 24-Month Follow-Up of a Phase 1 Clinical Study"

Per Fagerholm, Neil S. Lagali, Kimberley Merrett, W. Bruce Jackson, Rejean Munger, Yuwen Liu, James W. Polarek, Monica Söderqvist and May Griffith

Sci Transl Med 25 August 2010: Vol. 2, Issue 46, p. 46ra61 DOI: 10.1126/scitranslmed.3001022

Scientists use synthetic corneas to restore vision (Video Medical And Professional 2020).

Section Issues On Medicine: Disease