Hajime Matsumine

Electrophysiologic and functional evaluations of regenerated facial nerve defects with a tube containing dental pulp cells in rats.

Background: Dental pulp tissue contains Schwann and neural progenitor cells. Tissue-engineered nerve conduits with dental pulp cells promote facial nerve regeneration in rats. However, no nerve functional or electrophysiologic evaluations were performed. This study investigated the compound muscle action potential recordings and facial functional analysis of dental pulp cell regenerated nerve in rats. Methods: A silicone tube containing rat dental pulp cells in type I collagen gel was transplanted into a 7-mm gap of the buccal branch of the facial nerve in Lewis rats; the same defect was created in the marginal mandibular branch, which was ligatured. Compound muscle action potential recordings of vibrissal muscles and facial functional analysis with facial palsy score of the nerve were performed. Results: Tubulation with dental pulp cells showed significantly lower facial palsy scores than the autograft group between 3 and 10 weeks postoperatively. However, the dental pulp cell facial palsy scores showed no significant difference from those of autograft after 11 weeks. Amplitude and duration of compound muscle action potentials in the dental pulp cell group showed no significant difference from those of the intact and autograft groups, and there was no significant difference in the latency of compound muscle action potentials between the groups at 13 weeks postoperatively. However, the latency in the dental pulp cell group was prolonged more than that of the intact group. Conclusion: Tubulation with dental pulp cells could recover facial nerve defects functionally and electrophysiologically, and the recovery became comparable to that of nerve autografting in rats.

A polylactic acid non-woven nerve conduit for facial nerve regeneration in rats

This study developed a biodegradable nerve conduit with PLA non‐woven fabric and evaluated its nerve regeneration‐promoting effect. The buccal branch of the facial nerve of 8 week‐old Lewis rats was exposed, and a 7 mm nerve defect was created. A nerve conduit made of either PLA non‐woven fabric (mean fibre diameter 460 nm), or silicone tube filled with type I collagen gel, or an autologous nerve, was implanted into the nerve defect, and their nerve regenerative abilities were evaluated 13 weeks after the surgery. The number of myelinated neural fibres in the middle portion of the regenerated nerve was the highest for PLA tubes (mean ± SD, 5051 ± 2335), followed by autologous nerves (4233 ± 590) and silicone tubes (1604 ± 148). Axon diameter was significantly greater in the PLA tube group (5.17 ± 1.69 µm) than in the silicone tube group (4.25 ± 1.60 µm) and no significant difference was found between the PLA tube and autograft (5.53 ± 1.93 µm) groups. Myelin thickness was greatest for the autograft group (0.65 ± 0.24 µm), followed by the PLA tube (0.54 ± 0.18 µm) and silicone tube (0.38 ± 0.12 µm) groups, showing significant differences among the three groups. The PLA non‐woven fabric tube, composed of randomly‐connected PLA fibres, is porous and has a number of advantages, such as sufficient strength to maintain luminal structure. The tube has demonstrated a comparable ability to induce peripheral nerve regeneration following autologous nerve transplantation. Copyright

Adipocyte-derived and dedifferentiated fat cells promoting facial nerve regeneration in a rat model.

Background: Dedifferentiated fat cells, obtained from the ex vivo ceiling culture of mature adipocytes of mammals, have a high proliferative potential and pluripotency. The authors transplanted dedifferentiated fat cells into a nerve defect created in rat facial nerve and evaluated nerve regeneration ability. Methods: The buccal branch of the facial nerve of rats was exposed, and a 7-mm nerve defect was created. Green fluorescent protein–positive dedifferentiated fat cells prepared from adipocytes were mixed with type 1 collagen scaffold and infused into a silicone tube, which was then transplanted into the nerve defect in a green fluorescent protein–negative rat (the dedifferentiated fat group). Regenerated nerves were excised at 13 weeks after transplantation and examined histologically and physiologically. The findings were compared with those of autografts and silicone tubes loaded with collagen gel alone (the control group) transplanted similarly. Results: Axon diameter of regenerated nerve increased significantly in the dedifferentiated fat group compared with the control group, whereas no significant difference was found between the dedifferentiated fat and autograft groups. Myelin thickness was found to be largest in the autograft group, followed by the dedifferentiated fat and the control groups, showing significant differences between all pairs of groups. Evaluation of physiologic function of nerves by compound muscle action potential revealed a significantly better result in the dedifferentiated fat group than in the control group. The regenerated nerves in the dedifferentiated fat group had S100 and green fluorescent protein–double-positive Schwann-like supportive cells. Conclusion: After being transplanted into a facial nerve defect, dedifferentiated fat cells promoted the maturation of the regenerated nerve.

Vascularized versus nonvascularized island median nerve grafts in the facial nerve regeneration and functional recovery of rats for facial nerve reconstruction study.

Histological and physiological basis of the therapeutic efficacy of the vascularized autologous nerve graft in facial nerve regeneration remains poorly understood because of no established rat model. The left median nerve and median artery/vein of Lewis rats were collectively ligated, and harvested as a vascularized island median nerve, which was transplanted to a 7-mm gap in the left buccal branch of facial nerve. Nerve regeneration was investigated. The numbers of myelinated fibers, axon diameter, and myelin thickness were significantly higher in the vascularized nerve graft group than in the nonvascularized nerve graft group. Compound muscle action potential measurement showed that the parameters of vascularized group were similar to those in the intact control group. A vascularized median nerve graft resulted in better facial nerve regeneration outcomes.

Use of a bipedicled thin groin flap in reconstruction of postburn anterior neck contracture.

For cases of scar contracture following cervical burn trauma, after the contracture has been released, reconstructive free flap transfer is preferred over skin grafting to avoid the recurrence of contracture. It is still necessary, though, to augment this thin flap with sufficient skin by reproducing the submentocervical angle in the central region.1 However, by harvesting a bipedicled thin groin flap, vascularized on both sides by the superficial circumflex iliac arteries, we found that it became possible to thin the central area of this flap, making it suitable for use in the reconstruction of scar contractures following cervical burn trauma. We outline here the favorable results obtained through this technique.

Punch and spindle-shaped biopsies for collecting oral mucosal tissue for the fabrication of transplantable autologous epithelial cell sheets†

The oral mucosa is an easily accessible source of cells. Oral mucosal collection will be an essential surgical procedure for regenerative medicine and cell biological research. However, there is no current report that describes the details of the surgical procedure used for oral mucosal collection. Moreover, the number of cells that can be obtained has not been determined. Two different procedures, the punch biopsy and the spindle-shaped biopsy, were performed for the fabrication of transplantable autologous epithelial cell sheets. The mean values of the cells collected per square centimeter of tissue using the punch biopsy and the spindle-shaped biopsy were 76.8 ± 45 × 10(4) cells/cm(2) and 195.7 ± 120 × 10(4) cells/cm(2), respectively. There was no significant difference between the punch biopsy and the spindle-shaped biopsy. The coefficient of variation of the punch biopsy and the spindle-shaped biopsy was 58.9% and 69.8%, respectively. This result indicated that both procedures showed variations in the number of collected cells. Although the punch biopsy may be easier and simpler than the spindle-shaped biopsy, multiple punch biopsies may result in a more complicated procedure, and the spindle-shaped biopsy may be preferable when a large number of cells is necessary.

Improved "bell-bottom" flap surgical technique for syndactyly without skin graft.

Background: This study describes the use of a modified “bell-bottom” flap for treatment of partial syndactyly release that may avoid the use of skin grafting. Methods: A retrospective review of this procedure was performed for 12 interdigital space reconstructions. Patients were aged 1 to 5 years 6 months. The mean follow-up period was 24 months. The operations were performed to avoid skin grafting. The flap was designed in the narrow-spaced and fused interdigital region of syndactyly for preventing postoperative scar contracture and web formation. Results: Surgery was completed without skin grafting in all cases. The use of a modified flap allowed the construction of interdigital spaces with sufficient width, providing satisfactory cosmetic outcomes. No partial necrosis or complications were observed. No web formation, elevation of the interdigital space, or limited range of joint motion caused by contracture was observed during the 2-year follow-up period, and no secondary correction was needed. Conclusion: The present surgical technique may be a new surgical option for web release in which fingers are fused at a level lower than the midpoint between the proximal and distal interphalangeal joints. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Facial‐nerve regeneration ability of a hybrid artificial nerve conduit containing uncultured adipose‐derived stromal vascular fraction: An experimental study

This study investigated the potential of uncultured‐stromal‐vascular‐fraction (SVF) cells in promoting facial nerve regeneration in a rat model.

Facial nerve regeneration using basic fibroblast growth factor-impregnated gelatin microspheres in a rat model.

Basic fibroblast growth factor (bFGF) plays a crucial role in the regeneration of peripheral nerve defects by affecting nerve cells, Schwann cells and fibroblasts, and by promoting axon outgrowth from the proximal nerve stump. However, the use of exogenous bFGF for in vivo regeneration of the peripheral nerves is limited by its short in vivo half‐life. In this study, a drug delivery system for bFGF was developed that uses acidic gelatin hydrogel, which sustainably released bFGF in vivo over several weeks; its ability to promote peripheral nerve regeneration was also examined. In 8‐week‐old Lewis rats, 7‐mm gaps were made in the buccal branch of the left facial nerve. Acidic gelatin hydrogel microspheres (10 µl) with or without bFGF (50 µg) were infused into a 10 mm silicone tube using a micropipette, and the silicone tube was then implanted into the gap. A 1‐mm long nerve stump was inserted into each end of the tube. Histological examination at 7 weeks after implantation revealed (1) a significantly increased rate of nerve regeneration, (2) inducement of a number of regenerating nerve axons, and (3) a better degree of maturation of nerve axons in the bFGF microsphere group than that in the bFGF‐free microsphere group. Copyright

Treatment of skin avulsion injuries with basic fibroblast growth factor.

Summary: This report describes favorable outcomes in 9 patients with skin avulsion injuries of the extremities who underwent full-thickness skin grafting and basic fibroblast growth factor (bFGF) application. Following removal of contaminated subcutaneous fat tissue on the inside of skin, the avulsed skin was processed into a full-thickness skin graft, with as much of the skin used as possible irrespective of damage. Several drainage holes (5–10 mm in diameter) were made on the graft for drainage from the graft bed and to prevent seroma and hematoma formation. Genetically recombinant human bFGF was sprayed at a dose of 1 &mgr;g/cm2 onto the graft bed, which was then covered with the graft and sutured. Pressure immobilization with ointment gauzes and elastic bandages was administered for 1 week postoperatively, and the surface of the skin grafts that did not take was scraped away, preserving the revascularized dermal component on the debrided raw surface as much as possible. bFGF was sprayed again onto the debrided surface to promote epithelialization. Wound closure was achieved in all cases with conservative therapy. The surgical procedure was effective in preventing postoperative ulcer formation and scar contracture and resulted in wound healing with the formation of good-quality, flexible scars.