Guy Magalon

Characterization and Comparison of 5 Platelet-Rich Plasma Preparations in a Single-Donor Model

PURPOSE The purpose of this study was to compare the biological characteristics of platelet-rich plasma (PRP) obtained from 4 medical devices and a preparation developed in our laboratory using a single-donor model. METHODS Ten healthy persons donated blood that was processed to produce PRP by use of 4 commercial preparation systems and a protocol developed in our laboratory. Volumes and platelet, white blood cell (WBC), and red blood cell concentrations were recorded. The platelet activation status was assessed by flow cytometry. Enzyme-linked immunosorbent assay was used to determine the concentrations of vascular endothelial growth factor, platelet-derived growth factor AB, epidermal growth factor, and transforming growth factor β1. We calculated platelet capture efficiency, relative composition, and increase factors from whole blood in platelets and WBC, as well as platelet and growth factor (GF) doses, provided from each preparation. RESULTS Leukocyte-rich PRP was obtained with RegenPRP (RegenLab, Le Mont-sur-Lausanne, Switzerland) and the Mini GPS III System (Biomet Biology, Warsaw, IN) and provides PRP with higher proportions of red blood cells, WBCs, and neutrophils than leukocyte-poor PRP obtained with the Selphyl System (Selphyl, Bethlehem, PA), Arthrex ACP (Arthrex, Naples, FL), and the preparation developed in our laboratory. The highest platelet and GF concentrations and doses were obtained with the Mini GPS III System and the preparation developed in our laboratory. Different centrifugation protocols did not show differences in the percentages of activated platelets. Finally, a positive correlation between platelet doses and all the GFs studied was found, whereas a positive correlation between WBC doses and GFs was found only for vascular endothelial growth factor and epidermal growth factor. CONCLUSIONS In a single-donor model, significant biological variations in PRP obtained from different preparation systems were highlighted. The observed differences suggest different results for treated tissue and could explain the large variability in the clinical benefit of PRP reported in the literature. CLINICAL RELEVANCE Our findings will help clinicians to choose a system that meets their specific needs for a given indication.

La réparation nerveuse périphérique : 30 siècles de recherche

INTRODUCTION: Nerve injury compromises sensory and motor functions. Techniques of peripheral nerve repair are based on our knowledge regarding regeneration. Microsurgical techniques introduced in the late 1950s and widely developed for the past 20 years have improved repairs. However, functional recovery following a peripheral mixed nerve injury is still incomplete. STATE OF ART: Good motor and sensory function after nerve injury depends on the reinnervation of the motor end plates and sensory receptors. Nerve regeneration does not begin if the cell body has not survived the initial injury or if it is unable to initiate regeneration. The regenerated axons must reach and reinnervate the appropriate target end-organs in a timely fashion. Recovery of motor function requires a critical number of motor axons reinnervating the muscle fibers. Sensory recovery is possible if the delay in reinnervation is short. Many additional factors influence the success of nerve repair or reconstruction. The timing of the repair, the level of injury, the extent of the zone of injury, the technical skill of the surgeon, and the method of repair and reconstruction contribute to the functional outcome after nerve injury. CONCLUSION: This review presents the recent advances in understanding of neural regeneration and their application to the management of primary repairs and nerve gaps.

FK506 induces changes in muscle properties and promotes metabosensitive nerve fiber regeneration.

Accumulating evidence indicates that in addition to its immunosuppressant properties, FK506 (tacrolimus), an FDA-approved molecule, promotes nerve regeneration. However, the neuroprotective and neurotrophic effects of this molecule on sensitive fiber regeneration have never been studied. In order to fill this gap in our knowledge, we assessed the therapeutic potential of FK506 in a rat model of peripheral nerve repair. A 1-cm segment of left peroneal nerve was cut out and immediately autografted in an inverted position. After surgery, the animals were treated with FK506 (1.2 mg/kg/d) via an osmotic pump and compared to untreated animals. Recovery of use of the injured leg was assessed weekly for 12 weeks using a walking track apparatus and a camcorder. At the end of this period, motor and metabosensitive responses of the regenerated axons were recorded and histological analysis was performed. We observed that FK506 significantly: (1) increased the diameter of regenerated axons in the distal portion of the graft; (2) improved the responses of sensory neurons to metabolites such as potassium chloride and lactic acid; and (3) induced a fast-to-slow-fiber-type transition of the tibialis anterior muscle. Taken together, these data indicate that FK506 potentiates metabosensitive nerve fiber regeneration. Pharmacological studies of various dosages and concentrations of FK506 are required before recommending this drug for therapeutic treatment of nerve injuries.

Analyse des séquelles du lambeau antibrachial à pédicule radial: A propos d'une série de vingt-six cas

: The radial forearm flap is used extensively in hand and reconstructive surgery. We have performed 31 radial forearm flaps (15 free and 16 pedicled flaps) in 25 adults and 5 children. This series was analyzed in an attempt to minimize the sequelae of the upper limb and provide more specific indications for this flap. Vascular sequelae were assessed by Doppler and thermography examinations. The functional sequelae were appreciated by wrist motion and grasp strength examinations. Cutaneous sequelae were evaluated according to the time of healing and the quality of the scars. Several technical modifications may be proposed in order to try to minimize sequelae. As shown by our study, cutaneous sequelae are the most important and they must always be considered in the indication of this flap.

Prospective ex-vivo study on thermal effects in human skin phototypes II, IV and VI: a comparison between the 808, 1064, 1210 and 1320-nm diode laser

Background: Laser Assisted Skin Healing (LASH) was first introduced in 2001 by Capon and Mordon to prevent keloids and hypertrophic scars. LASH requires homogenous heating throughout the full thickness of the skin around the wound. However, LASH therapy with 808-nm diode laser is deemed to be only applicable for phototype I–IV due to melanin absorption. This prospective ex-vivo study aims to evaluate the thermal effects of different wavelengths (808, 1064, 1210 and 1320 nm) on human skin phototype II, IV and VI. Material and methods: Laser shots were applied on skin explants phototypes II, IV and VI. The following laser settings were used: 808, 1064, 1210 and 1320-nm diode laser, Spot size 20 × 3.7 mm, Power 3 W, Irradiance 4 W/cm², 50 shots for each phototype and wavelength. The surface temperature at 2 and 4-mm depth respectively was evaluated by an infrared camera and a low inertia micro thermocouple. Results: For the 1064, 1210 and 1320-nm wavelengths, the temperature gradient between the surface and 2-mm depth after an irradiation time of 15 s was less than 4.0°C for each phototype. For the 808 nm, the gradient was 0.8°C and 4.4°C in phototype II and IV respectively, but reached 17.2°C in phototype VI. Strong absorption by melanin of skin phototype VI induced unwanted temperature increases at the dermis-epidermis junction, making this wavelength unsuitable for LASH therapy for this phototype. Among the three other wavelengths, the discussion section indicates strong blood absorption at 1064 nm and presents both 1210 and 1320 nm as excellent compromises for LASH therapy across the whole range of phototypes. Conclusion: Being poorly absorbed by melanin, both 1210 and 1320-nm wavelengths ensure homogeneity of temperature throughout the full skin explant thickness. Their possible utilization for efficient LASH therapy should now be confirmed by prospective in vivo studies.

Mechano- and metabosensitive alterations after injection of botulinum toxin into gastrocnemius muscle

This study was designed to investigate effects of motor denervation by Clostridium botulinum toxin serotype A (BoNT/A) on the afferent activity of fibers originating from the gastrocnemius muscle of rats. Animals were randomized in two groups, 1) untreated animals acting as control and 2) treated animals in which the toxin was injected in the left muscle. Locomotor activity was evaluated once per day during 12 days with a test based on footprint measurements of walking rats (sciatic functional index). At the end of the functional assessment period, electrophysiological tests were used to measure muscle properties, metabosensitive afferent fiber responses to chemical (KCl and lactic acid) injections, electrically induced fatigue (EIF), and mechanosensitive responses to tendon vibrations. Additionally, ventilatory response was recorded during repetitive muscle contractions. Then, rats were sacrificed, and the BoNT/A‐injected muscles were weighed. Twelve days postinjection we observed a complete motor denervation associated with a significant muscle atrophy and loss of force to direct muscle stimulation. In the BoNT/A group, the metabosensitive responses to KCl injections were unaltered. However, we observed alterations in responses to EIF and to 1 mM of lactic acid (which induces the greatest activation). The ventilatory adjustments during repetitive muscle activation were abolished, and the mechanosensitive fiber responses to tendon vibrations were reduced. These results indicate that BoNT/A alters the sensorimotor loop and may induce insufficient motor and physiological adjustments in patients in whom a motor denervation with BoNT/A was performed.