Membranes Prepared from Recombinant RGD-Silk Fibroin as Substrates for Human Corneal Cells.

A recombinant formulation of silk fibroin containing the arginine-glycine-aspartic acid (RGD) cell-binding motif (RGD-fibroin) offers potential advantages for the cultivation of corneal cells. Thus, we investigated the growth of corneal stromal cells and epithelial cells on surfaces created from RGD-fibroin, in comparison to the naturally occurring Bombyx mori silk fibroin. The attachment of cells was compared in the presence or absence of serum over a 90 min period and analyzed by quantification of dsDNA content. Stratification of epithelial cells on freestanding membranes was examined by confocal fluorescence microscopy and optimized through use of low molecular weight poly(ethylene glycol) (PEG; 300 Da) as a porogen, the enzyme horseradish peroxidase (HRP) as a crosslinking agent, and stromal cells grown on the opposing membrane surface. The RGD-fibroin reduced the tendency of stromal cell cultures to form clumps and encouraged the stratification of epithelial cells. PEG used in conjunction with HRP supported the fabrication of more permeable freestanding RGD-fibroin membranes, that provide an effective scaffold for stromal-epithelial co-cultures. Our studies encourage the use of RGD-fibroin for corneal cell culture. Further studies are required to confirm if the benefits of this formulation are due to changes in the expression of integrins, components of the extracellular matrix, or other events at the transcriptional level.

Tracheostomy in free-flap reconstruction of the oral cavity: can it be avoided? A cohort study of 187 patients.

BACKGROUND: Head and neck surgeons are moving away from routine tracheostomy in free-flap reconstruction. We reviewed prophylactic tracheostomy use in patients undergoing oral cavity or oropharynx free-flap reconstruction to identify patient groups who avoided tracheostomy. Secondary aims were to describe complications associated with and without tracheostomy. METHODS: A retrospective cohort study was undertaken, using a prospectively maintained database. Inclusion criteria was free-flap reconstruction for an oral cavity or oropharyngeal defect, excluding partial or total laryngectomy. Variables collected included demographics, comorbidity, American Society of Anesthesiologists grade, Charlson Comorbidity Index, tumour site and subsite, extent of resection, surgery duration, tracheostomy, complications, return to theatre and re-intubation. RESULTS: A total of 344 head and neck free-flap reconstructions were performed between January 2017 and July 2019. A total of 164 (87.7%) oral cavity and 23 (12.3%) oropharyngeal reconstructions were included totalling 187 free flaps. A total of 107 (57.2%) were males and 80 (42.8%) females, mean age 62.4 years (range 21-89). Of 187 patients, 100 (53.5%) underwent prophylactic tracheostomy at time of reconstruction. Longer operative time (P < 0.001), resection site (P < 0.001), number of subsites resected (P = 0.007), segmental mandibulectomy (P = 0.04), lip-split (P = 0.05), floor of mouth resection (P < 0.001), lingual release (P = 0.007), glossectomy (P < 0.001), extent of tongue resection (P < 0.001), extent of hard palate resection (P = 0.04), soft palate resection (P < 0.001) and double free-flap reconstruction (P = 0.04) were associated with tracheostomy use. CONCLUSION: A personalized approach to postoperative airway management allowed almost half of our cohort to avoid tracheostomy. In high-volume institutions with the necessary expertise and support, appropriately selected patients may be safely managed without routine tracheostomy.

Optically robust, highly permeable and elastic protein films that support dual cornea cell types.

Damaged corneas can lead to blindness. Due to the worldwide shortage of donor corneas there is a tremendous unmet demand for a robust corneal replacement that supports growth of the major corneal cell types. Commercial artificial corneas comprise plastic polymers that do not adequately support diverse cell growth. We present a new class of protein elastomer-dominated synthetic corneas with attractive performance that intimately couple biologically active tropoelastin to mechanically robust and durable protein silk. Fabricated films substantially replicate the natural cornea physically and by interacting with both key cells types used in cornea repair. Performance encompasses optical clarity at high transmittance, compatible refractive index, substantial glucose permeability, compliant mechanical properties, and support of both growth and function of corneal epithelial and endothelial cells.

Mounting of Biomaterials for Use in Ophthalmic Cell Therapies.

When used as scaffolds for cell therapies, biomaterials often present basic handling and logistical problems for scientists and surgeons alike. The quest for an appropriate mounting device for biomaterials is therefore a significant and common problem. In this review, we provide a detailed overview of the factors to consider when choosing an appropriate mounting device including those experienced during cell culture, quality assurance, and surgery. By way of example, we draw upon our combined experience in developing epithelial cell therapies for the treatment of eye diseases. We discuss commercially available options for achieving required goals and provide a detailed analysis of 4 experimental designs developed within our respective laboratories in Australia, the United Kingdom, and Belgium.