Autologous platelet-poor plasma gel for injection laryngoplasty

Abstract

Purpose: To overcome the potential disadvantages of the use of foreign materials and autologous fat or collagen, we introduce here an autologous plasma gel for injection laryngoplasty. The purpose of this study was to present a new injection material, a plasma gel, and to discuss its clinical effectiveness.

Materials and methods: From 2 mL of blood, the platelet poor serum layer was collected and heated at 100°C for 12 min to form a plasma gel. The plasma gel was then injected into a targeted site; the safety and efficacy thereof were evaluated in 30 rats. We also conducted a phase I/II clinical study of plasma gel injection laryngoplasty in 11 unilateral vocal fold paralysis patients.

Results: The plasma gel was semi-solid and an easily injectable material. Of note, plasma gel maintains the same consistency for up to 1 year in a sealed bottle. However, exposure to room air causes the plasma gel to disappear within 1 month. In our animal study, the autologous plasma gel remained in situ for 6 months in animals with minimal inflammation. Clinical study showed that vocal cord palsy was well compensated for with the plasma gel in all patients at two months after injection with no significant complications. Jitter, shimmer, maximum, maximum phonation time (MPT) and mean voice handicap index (VHI) also improved significantly after plasma gel injection. However, because the injected plasma gel was gradually absorbed, 6 patients needed another injection, while the gel remained in place in 2 patients.

Conclusion: Injection laryngoplasty with autologous plasma gel may be a useful and safe treatment option for temporary vocal cord palsy.

Keywords: Plasma gel; acoustical analysis; injection; laryngoplasty; vocal cord palsy.

Fig. 1

(A) Taking a whole blood sample and centrifuging at 3000 RPM for 15 min. (B) The blood was separated into three layers. (C) The platelet-poor serum layer was collected and pipette into sterilized injection bottles. (D) The injection bottle was attached to a dental syringe and heated at 100℃ for 12 minutes. The collected serum finally turned to plasma gel. (E) The plasma gel was a semi-solid and easily injectable material that was stable at the injection site. (F) The plasma gel was maintained over 1 year in the sterilized injection bottle, but exposed to room air, the plasma gel disappeared within 1 month. (G) Electron microscope findings of plasma gel: the plasma gel showed the typical shape of protein structures on an electron microscope.

Fig. 2

The findings of injected plasma gel in rats: (A) 24 hours after plasma gel injection. (B) At 1 month. (C) At 3 months. (D) Six months later the injected material nearly disappeared. (E and I) Histological findings of the plasma gel at the subcutaneous layer of rats, 1 day after injection, there was a slight marked cellular infiltration of inflammation cells. (F and J) 1 month later, there was no evidence of infiltration of acute inflammation cells. (G and K) 3 months later, a mature fibrous capsule surrounded the plasma gel deposit. (H and L) There was no visible fibrous capsule or inflammation cell infiltration. Arrow: remnant of the plasma gel (hematoxylin and eosin stain, E-H ×40, I-L ×100). (M) Serial changes of the injected autologous plasma gel at the subcutaneous layer of rats.

Fig. 3

Serial changes in injected plasma gel in patients with unilateral vocal palsy. This patient was treated for left vocal cord palsy. (A) Left vocal cord palsy. The vocal cord did not move symmetrically. The vocal cord did not close and the voice was husky. (B) One month after injection, the left vocal cord became straightened, the color was slightly yellow, and the vocal cord closed completely. (C) Three months after injection, the glottis gap was re-developed, but was not wider than pre-injection status. (D-G) Changes in maximum phonation time and vocal acoustics after injection laryngoplasty with plasma gel. NHR, noise to harmony ratio; OP, operation.