Michael W. Neumeister

Successful transplantation of three tissue-engineered cell types using capsule induction technique and fibrin glue as a delivery vehicle.

Recent advances in cell biology and tissue engineering have used various delivery vehicles for transplanting varying cell cultures with limited success. These techniques are frequently complicated by tissue necrosis, infection, and resorption. The purpose of this study was to investigate whether urothelium cells, tracheal epithelial cells, and preadipocytes cultured in vitro could be successfully transplanted onto a prefabricated capsule surface by using fibrin glue as a delivery vehicle, with the ultimate goal for use in reconstruction. In the first step of the animal study, tissue specimens (bladder urothelium, tracheal epithelial cells, epididymal fat pad) were harvested for in vitro cell culturing, and a silicone block was implanted subcutaneously or within the anterior rectus sheath to induce capsule formation. After 6 to 10 days, when primary cultures were confluent, the animals were re-anesthetized, the newly formed capsule pouches were incised, and the suspensions of cultured urothelia cells (n = 40), tracheal epithelial cells (n = 32), and preadipocytes (n = 40) were implanted onto the capsule surface in two groups, one using standard culture medium as a delivery vehicle and the second using fibrin glue. Histologic sections were taken, and different histomorphologic studies were performed according to tissue type. Consistently in all animals, a highly vascularized capsule was induced by the silicon material. In all animals in which the authors used fibrin glue as a delivery vehicle, they could demonstrate a successful reimplantation of cultured urothelium cells, tracheal epithelial cells, or preadipocytes. Their animal studies showed that capsule induction in combination with fibrin glue as a delivery vehicle is a successful model for transplantation of different in vivo cultured tissue types.

Botulinum toxin type A in the treatment of Raynaud's phenomenon.

PURPOSE Raynauds phenomenon is a vasospastic disorder of the palmar and digital vessels of the hand and feet that can lead to ischemic ulcers, pain, and loss of function. This study is a review of patients I have injected with botulinum toxin type A for patients with Raynauds phenomenon. METHODS Raynauds patients were injected with 50 to 100 units of onabotulinumtoxinA to improve perfusion of the digits. An institutional review board-approved retrospective review was undertaken to analyze outcomes. Laser Doppler scans were performed before and after injection to quantitatively measure perfusion. RESULTS A total of 14 men and 19 women with Raynauds phenomenon were injected with onabotulinumtoxinA. All but 5 patients experienced improved vascularity and relief of pain. Laser Doppler scans illustrated notable improvement in perfusion. Five patients had repeat injections for recurrent pain. CONCLUSIONS Botulinum toxin appears to improve perfusion of the hand after direct injection around the neurovascular bundles. Further investigations are warranted to identify the exact mode of action in relieving vasospasm and alleviating pain.

Mutilating hand injuries: principles and management

The objectives of the treatment of mutilating hand injuries are to insure patients survival, limb survival and ultimately limb function. Initially, patients are stabilized and cleared of other potentially life threatening trauma. The cornerstone to the early intra-operative management of the mangled hand includes irrigation and debribement. Skeletal stabilization, revascularization, replantation or the use of spare parts to restore functions are addressed at the initial surgery. Subsequent second or third look surgeries may be required to procure a clean wound bed. Regional flaps and free tissue transfer provides definitive coverage than soft tissue is required. Secondary procedures such as tenolysis, joint mobilization or toe transfers may be needed to restore dexterity to the healed yet dysfunctional hand. Adherence to sound safe principles help prevent further mobidity while fostering the restoration of hand function to return the patient to gainful activities.

Vascularized tissue-engineered ears.

Background: A paucity of appropriate regional and local matching tissue can compromise the reconstruction efforts in areas of the body that require specialized tissue. The current study uses techniques of vascular prefabrication, tissue culturing, and capsule formation to form a vascularized ear construct that is reliably transferable on its blood supply. Methods: Thirty male Wistar rats (250 to 350 g) were anaesthetized. An incision was made over the right lower abdominal wall. A pocket was formed by blunt dissection just below the panniculus carnosus. A separate incision was made over the right femoral vessels, which were then isolated and transected distally. The vessels were transposed in a subcutaneous plane to the abdominal wound. A silicone mold in the shape of an ear (2 × 1.5 cm) was placed over the transposed vessels in the abdominal wound pocket. The wounds were closed. Auricular cartilage was minced, washed, and cultured. After 14 days, the chondrocyte culturing was complete and a vascularized capsule based on the incorporated, transposed femoral vessels was formed. The abdominal incision was then reopened, an incision was made in the lateral capsule, and the cultured chondrocytes were introduced into the molded capsule. Study groups included capsules filled with chondrocytes only, chondrocytes and a fibrin glue carrier, and the fibrin glue only. The capsule was closed and the wounds sutured. The prefabricated, prelaminated construct was isolated on its vascular pedicle 14 days later and traversed microsurgically to the contralateral leg vessels. Histologic analysis was performed. Results: All 30 capsules were completely vascularized and could be reliably isolated and transferred microsurgically on the transposed femoral vessels. The pedicle, being incorporated directly into the capsule, provided the dominant blood supply to the construct. None of the capsules with the fibrin glue only retained any shape and all were devoid of cartilage. Similarly, there was no evidence of retained cartilage in the capsules filled with chondrocytes alone. All capsules with the chondrocytes and the fibrin carrier had mature shaped cartilage preserved. External molds were required to maintain the shape of the ear. Extrusion, although almost uniform in the group with external molds, did not interfere with the end construct shape or vascularity. When molds were used, four of six had excellent maintenances of shape and two of six had only minor superior pole deformation. All constructs were reliably transferred as free flaps. Conclusions: The authors have shown that transposing a vascular pedicle to a subcutaneously placed silicone block will result in a vascular capsule that can be mobilized and transferred based solely on the pedicle. Although the capsule provides vascularity to the chondrocytes, the cultured cartilage will fill the shape of the silicone mold only if an appropriate carrier such as fibrin glue is used and an external mold is applied.

Efficacy and safety of a fibrin sealant for adherence of autologous skin grafts to burn wounds: Results of a phase 3 clinical study

The objective of this phase 3, multicentered, prospective, randomized, evaluator-blinded, clinical study was to compare skin graft adherence utilizing a fibrin sealant containing 4 IU/ml thrombin (FS 4IU VH S/D [FS 4IU VH S/D will be marketed under the trade name ARTISS upon licensure in the United States]) to graft adherence utilizing staples in burn patients requiring wound excision and skin grafting. FS 4IU VH S/D was compared with staples in 138 patients. Patients had burn wounds measuring ≤40% of total body surface area with two comparable test sites measuring between 1 and 4% total body surface area each. Wound closure at day 28 was assessed using test site planimetry and review of day 28 photographs by three independent blinded evaluators (primary endpoint analysis). Secondary efficacy measures included hematoma/seroma on day 1, engraftment on day 5, and wound closure on day 14. Investigator and patient-reported outcomes were also assessed. The proportion of test sites with complete wound closure at day 28 was 70.3% in FS 4IU VH S/D treated sites and 65.8% in stapled sites, as assessed by planimetry. Blinded review of day 28 photographs confirmed that the rate of complete wound closure was similar between the two treatments, although the overall assessed rates of closure were lower than those determined by planimetry: FS 4IU VH S/D (43.3%) and staples (37.0%). The lower limit of the 97.5% confidence interval of the difference between FS 4IU VH S/D and staples was −0.029, which is above the predefined noninferiority margin of −0.1. Therefore, FS 4IU VH S/D is at least as efficacious as staples at the 97.5% one-sided level for complete wound closure by day 28. Hematoma/seroma on day 1 occurred at significantly (P < .0001) fewer FS 4IU VH S/D-treated sites (29.7% [95% CI 22.2–38.1%]) compared with stapled sites (62.3% [95% CI 53.7–70.4%]). Engraftment on day 5 was deemed to be 100% in 62.3% (95% CI 53.7–70.4%) of the FS 4IU VH S/D-treated sites and 55.1% (95% CI 46.4–63.5%) of the stapled sites (P = .0890). Complete wound closure by day 14 occurred in 48.8% (95% CI 39.9–57.8%) of the FS 4IU VH S/D treated sites and 42.6% (95% CI 34.0–51.6%) of the stapled sites (P = .2299). FS 4IU VH S/D scored significantly better than staples for all investigator-assessed outcomes, namely quality of graft adherence (P < .0001), preference for method of fixation (P < .0001), satisfaction with graft fixation (P < .0001), and overall quality of healing (P < .0001). Likewise, FS 4IU VH S/D scored significantly better than staples for all patient-assessed outcomes, namely anxiety about pain (P < .0001) and treatment preference (P <.0001). The safety profile of FS 4IU VH S/D was excellent as indicated by the lack of any related serious adverse experiences. These findings demonstrate that FS 4IU VH S/D is safe and effective for attachment of skin grafts, with outcomes at least as good as or better than staple fixation.

Immediate thumb extension following extensor indicis proprius-to-extensor pollicis longus tendon transfer using the wide-awake approach.

Background: The elective use of low-dose epinephrine in hand surgery has allowed for the performance of simple operative procedures with tourniquet-free pure local anesthesia (the wide-awake approach). The absence of general anesthesia or sedation has, in turn, allowed for the observation of how quickly the sensorimotor cortex adapts following procedures such as tendon transfer. Methods: Seven patients underwent a wide-awake transfer of the extensor indicis proprius to the extensor pollicis longus between February of 2002 and May of 2005 for restoration of thumb extension using local lidocaine with epinephrine alone. One of the seven patients experienced rupture of the initial transfer, necessitating transfer of the extensor carpi radialis longus to the extensor pollicis longus using the wide-awake approach. Results: All seven patients were able to extend their thumbs fully by means of extensor indicis proprius intraoperatively immediately following transfer suture placement. Restoration of function was not ablated by loss of proprioception or visual feedback. At a mean follow-up of 15 months, thumb extension was restored to within normal limits in the affected thumb, with a slight decrease in grip and tripod pinch strength. Conclusions: The wide-awake approach has allowed the authors to adjust tendon transfer tension with active movement before skin closure without the risks associated with general or regional anesthesia. In addition, it has allowed them to observe immediate cortical adaptation in the context of a simple tendon transfer. The authors hypothesize that the brain’s ability to immediately use extensor indicis proprius for thumb extension stems from the activation of preexisting synergistic cortical finger movement programs.

Safe Treatment of Trigger Finger with Longitudinal and Transverse Landmarks: An Anatomic Study of the Border Fingers for Percutaneous Release

Transverse landmarks have recently been determined to predict the proximal and distal edges of the A1 pulley for trigger finger release. Percutaneous A1 pulley release has been discouraged for the border digits because of the risk of injury to the neurovascular structures of the index and small fingers. The purpose of the study was to identify longitudinal surface landmarks to prevent injury to the neurovascular bundles during percutaneous A1 pulley release of the ulnar and radial border digits. Longitudinal surface landmarks were identified and marked on 29 cadaver hands. Proximal and distal landmarks for the longitudinal vector through which the A1 pulley of the small finger was released include the midline of the proximal digital crease and the scaphoid tubercle. Proximal and distal landmarks for the longitudinal line through which the index finger A1 pulley was released include the midline of proximal digital crease and radial edge of the pisiform. Longitudinal incisions were performed between these landmarks, straight through the skin and deep enough to score the A1 pulley. The distance of the medial edge of the neurovascular structures from the longitudinal incision in the A1 pulley was measured for each small finger and index finger. Using these longitudinal landmarks for the index and small fingers, none of the neurovascular structures was injured while performing these longitudinal incisions through the skin, scoring the A1 pulley. In fact, the average distance for the neurovascular structures from the longitudinal vector of the small finger was 5.4 ± 1.4 mm radially and 6.7 ± 1.9 mm ulnarly. The average distance for the neurovascular structures from the longitudinal line of the index finger was 8.5 ± 1.8 mm radially and 6.2 ± 1.7 mm ulnarly. Based on the findings of this anatomical study, these longitudinal landmarks can be used to avoid injury to neurovascular structures in the management of trigger finger involving the border digits with steroid-injection, open, or percutaneous A1 pulley release.

Continuous Postoperative Catheter Irrigation is not Necessary for the Treatment of Suppurative Flexor Tenosynovitis

The records of 75 patients admitted with pyogenic flexor tenosynovitis at two academic centers were reviewed. The functional outcomes of patients who received intraoperative irrigation only (n=20) and those that had both intraoperative irrigation and continuous postoperative irrigation (n=55) were compared. There were no statistically significant differences between the outcomes in the two groups.

Local hypothermia during early reperfusion protects skeletal muscle from ischemia-reperfusion injury.

Amputated tissue maintained in a hypothermic environment can endure prolonged ischemia and improve replantation success. The authors hypothesized that local tissue hypothermia during the early reperfusion period may provide a protective effect against ischemia-reperfusion injury similar to that seen when hypothermia is provided during the ischemic period. A rat gracilis muscle flap model was used to assess the protective effects of exposing skeletal muscle to local hypothermia during ischemia only (p = 18), reperfusion only (p = 18), and both ischemia and reperfusion (p = 18). Gracilis muscles were isolated and exposed to hypothermia of 10 degrees C during 4 hours of ischemia, the initial 3 hours of reperfusion, or both periods. Ischemia-reperfusion outcome measures used to evaluate muscle flap injury included muscle viability (percent nitroblue tetrazolium staining), local edema (wet-to-dry weight ratio), neutrophil infiltration (intramuscular neutrophil density per high-power field), neutrophil integrin expression (CD11b mean fluorescence intensity), and neutrophil oxidative potential (dihydro-rhodamine oxidation mean fluorescence intensity) after 24 hours of reperfusion. Nitroblue tetrazolium staining demonstrated improved muscle viability in the experimental groups (ischemia-only: 78.8 +/- 3.5 percent, p < 0.001; reperfusion-only: 80.2 +/- 5.2 percent, p < 0.001; and ischemia-reperfusion: 79.6 +/- 7.6 percent, p < 0.001) when compared with the nonhypothermic control group (50.7 +/- 9.3 percent). The experimental groups demonstrated decreased local muscle edema (4.09 +/- 0.30, 4.10 +/- 0.19, and 4.04 +/- 0.31 wet-to-dry weight ratios, respectively) when compared with the nonhypothermic control group (5.24 +/- 0.31 wet-to-dry weight ratio; p < 0.001, p < 0.001, and p < 0.001, respectively). CD11b expression was significantly decreased in the reperfusion-only (32.65 +/- 8.75 mean fluorescence intensity, p < 0.001) and ischemia-reperfusion groups (25.26 +/- 5.32, p < 0.001) compared with the nonhypothermic control group (62.69 +/- 16.93). There was not a significant decrease in neutrophil CD11b expression in the ischemia-only group (50.72 +/- 11.7 mean fluorescence intensity, p = 0.281). Neutrophil infiltration was significantly decreased in the reperfusion-only (20 +/- 11 counts per high-power field, p = 0.025) and ischemia-reperfusion groups (23 +/- 3 counts, p = 0.041) compared with the nonhypothermic control group (51 +/- 28 counts). No decrease in neutrophil density was observed in the ischemia-only group (40 +/- 15 counts per high-power field, p = 0.672) when compared with the nonhypothermic control group (51 +/- 28 counts). Finally, dihydrorhodamine oxidation was significantly decreased in the reperfusion-only group (45.83 +/- 11.89 mean fluorescence intensity, p = 0.021) and ischemia-reperfusion group (44.30 +/- 11.80, p = 0.018) when compared with the nonhypothermic control group (71.74 +/- 20.83), whereas no decrease in dihydrorhodamine oxidation was observed in the ischemia-only group (65.93 +/- 10.3, p = 0.982). The findings suggest a protective effect of local hypothermia during early reperfusion to skeletal muscle after an ischemic insult. Inhibition of CD11b expression and subsequent neutrophil infiltration and depression of neutrophil oxidative potential may represent independent protective mechanisms isolated to local tissue hypothermia during the early reperfusion period (reperfusion-only and ischemia-reperfusion groups). This study provides evidence for the potential clinical utility of administering local hypothermia to ischemic muscle tissue during the early reperfusion period.

Improvement in burn wound infection and survival with antimicrobial peptide D2A21 (Demegel)

Naturally occurring antimicrobial peptides have been discovered in both plants and animals. Many of these peptides demonstrate impaired activity or cytotoxicity when applied exogenously. Synthetically engineered antimicrobial peptides have been designed to increase potency and activity against bacteria and fungus yet remain noncytotoxic. The antimicrobial peptide D2A21 (Demegel) has already demonstrated significant activity in vitro against many common hospital pathogens. The purpose of this study was to evaluate the effects of D2A21 in an in vivo infected burn-wound model, examining both quantitative cultures of the wound and survival of the animal. Forty-four Wistar rats were subjected to a 23 percent total body surface area scald burn. Pseudomonas aeruginosa was administered topically with 108 organisms and wounds were then evaluated at day 1, 2, or 3 for eschar and subeschar muscle quantitative culture. The experimental group was treated daily with 1.5% topical D2A21. The control group was treated with control gel. A second group of Wistar rats (n = 14) were burned and given a 107 inoculum of the same Pseudomonas and evaluated to 14 days for survival and weight changes. This group was subdivided into rats receiving either topical D2A21 or control base daily. The quantitative biopsy results demonstrated that D2A21-treated wounds had no bacterial growth in burn eschar at day 2 or 3, whereas control animals demonstrated growth at greater than 105 organisms by day 2. Subeschar muscle cultures also demonstrated significantly less bacterial invasion compared with controls on each day tested. D2A21-treated animals had an 85.7 percent survival compared with 0 percent survival in controls. Furthermore, the D2A21-treated groups demonstrated maintenance of body weights, whereas controls had significant weight loss with time. In conclusion, D2A21 demonstrates significant antibacterial activity against Pseudomonas, sterilizing burn eschar and decreasing subeschar bacterial load, allowing for a markedly significant improvement in survival in this infected burn-wound model.