Microglia replacement by microglia transplantation (Mr MT) in the adult mouse brain.

Mutations in microglia may cause brain disorders. Replacement of dysfunctional microglia by allogeneic wild-type microglia from bone marrow transplantation (Mr BMT) or peripheral blood can correct the gene deficiency at the brain-wide scale but cannot achieve precise replacement at specific brain regions. Here, we introduce a strategy with potential clinical relevance-microglia replacement by microglia transplantation (Mr MT), combining tamoxifen-induced ablation of Mr BMT cells and intracranial injection of microglia to mouse brain, to achieve region-sepcific microglia replacement. The original abbreviation of this microglia replacement strategy is mrMT. We hereby change the name to Mr MT. For complete details on the use and execution of this protocol, please refer to Xu et al. (2020).

Effects of tissue culture on the biomechanical properties of porcine meniscus explants.

BACKGROUND: The meniscus is critical for the normal functioning of the knee joint. The specific aim of this study was to validate an in vitro culture model of meniscus explants for testing the impact of culture conditions on meniscus biomechanical properties. We hypothesized that culturing menisci in the presence of intermediate and high concentration of serum would have a positive effect on the compressive stiffness of the meniscus. METHODS: Unconstrained microindentation testing was performed on porcine meniscus explants cultured with varying concentrations 1%, 5%, or 10% of fetal bovine serum media. Meniscus explants that were not cultured were used as a control. These tests quantified the Young's Modulus of the listed groups of cultured and uncultured explant tissues. FINDINGS: The Young's modulus for 10% cultured explants were significantly higher compared to the control, 1%, and 5% cultured meniscus explants. There was no statistical significance when the Young's modulus between control, 1%, and 5% cultured explants were compared. INTERPRETATION: These results suggest that low concentrations of serum do not impart an anabolic effect on meniscus tissue explant biomechanical properties.

Comparison of tissue loss by different punches: A new A-design.

OBJECTIVES: To compare the amount of tissue loss using different FUE punches. MATERIALS AND METHODS: The study was conducted in 5 patients undergoing hair restoration surgery by FUE. Four different kinds of punches were used, that is, sharp, blunt, serrated, and new "A-design." All the punches had a total cutting edge of 0.8 mm. In each patient, 4 punches were used to make insertion at right angle with the skin. Immediately after the punch use, the diameter of the hole was measured. The same areas were also measured after 24 hours and after 1 month. The data were collected and analyzed by Multiple t test (with Bonferroni's correction). RESULTS: The average size of the wound immediately at the end of the procedure was 0.826 mm for sharp, 0.858 mm for blunt, 0.892 mm for serrated, and 0.932 mm for A-design. Similarly, the wounds decreased to 0.752, 0.778, 0.774, and 0.696 mm for sharp, blunt, serrated, and A-design, respectively, after 24 hours. The final wound/scar size was 0.640 mm for punch, 0.660 mm for blunt punch, 0.668 mm for serrated punch, and 0.598 mm for A-design punch after 1 month. CONCLUSION: The new A-design resulted in the minimum scar size after 1 month.

Novel experimental surgical strategy to prevent traumatic neuroma formation by combining a 3D-printed Y-tube with an autograft.

OBJECTIVE Traumatic neuromas may develop after nerve injury at the proximal nerve stump, which can lead to neuropathic pain. These neuromas are often resistant to therapy, and excision of the neuroma frequently leads to recurrence. In this study, the authors present a novel surgical strategy to prevent neuroma formation based on the principle of centro-central anastomosis (CCA), but rather than directly connecting the nerve ends to an autograft, they created a loop using a 3D-printed polyethylene Y-shaped conduit with an autograft in the distal outlets. METHODS The 3D-printed Y-tube with autograft was investigated in a model of rat sciatic nerve transection in which the Y-tube was placed on the proximal sciatic nerve stump and a peroneal graft was placed between the distal outlets of the Y-tube to form a closed loop. This model was compared with a CCA model, in which a loop was created between the proximal tibial and peroneal nerves with a peroneal autograft. Additional control groups consisted of the closed Y-tube and the extended-arm Y-tube. Results were analyzed at 12 weeks of survival using nerve morphometry for the occurrence of neuroma formation and axonal regeneration in plastic semi-thin sections. RESULTS Among the different surgical groups, the Y-tube with interposed autograft was the only model that did not result in neuroma formation at 12 weeks of survival. In addition, a 13% reduction in the number of myelinated axons regenerating through the interposed autograft was observed in the Y-tube with autograft model. In the CCA model, the authors also observed a decrease of 17% in the number of myelinated axons, but neuroma formation was present in this model. The closed Y-tube resulted in minimal nerve regeneration inside the tube together with extensive neuroma formation before the entrance of the tube. The extended-arm Y-tube model clearly showed that the majority of the regenerating axons merged into the Y-tube arm, which was connected to the autograft, leaving the extended plastic arm almost empty. CONCLUSIONS This pilot study shows that our novel 3D-printed Y-tube model with interposed autograft prevents neuroma formation, making this a promising surgical tool for the management of traumatic neuromas.

[Benefits of volumetric to facial rejuvenation. Part 1: Fat grafting]. / Apport de la volumétrie au rajeunissement facial. Partie 1 : greffe adipocytaire.

For a number of years, a volumetric approach using autologous fat injection has been implemented to improve cosmetic outcome in face-lift procedures and to achieve lasting rejuvenation. Autologous fat as filling tissue has been used in plastic surgery since the late 19th century, but has only recently been associated to face lift procedures. The interest of the association lies on the one hand in the pathophysiology of facial aging, involving skin sag and loss of volume, and on the other hand in the tissue induction properties of grafted fat, "rejuvenating" the injected area. The strict methodology consisting in harvesting, treating then injecting an autologous fat graft is known as LipoStructure® or lipofilling. We here describe the technique overall, then region by region. It is now well known and seems simple, effective and reproducible, but is nevertheless delicate. For each individual, it is necessary to restore a harmonious face with well-distributed volumes. By associating volumetric to the face lift procedure, the plastic surgeon plays a new role: instead of being a tailor, cutting away excess skin, he or she becomes a sculptor, remodeling the face to restore the harmony of youth.

Introduction of neurosupportive cells into processed acellular nerve allografts results in greater number and more even distribution when injected compared to soaking techniques.

OBJECTIVES: Processing necessary to remove immunogenic components of nerve allograft renders it acellular. Seeding with supportive cells may improve axon regeneration. We aim to identify the method associated with implantation of the greatest volume and most even distribution of cells. METHODS: Hypodermic needle injection was compared to soaking in solution under both normal and pressurized conditions after micropuncture of the allograft. Distribution within the allograft was measured using an in vitro model of fluorescent beads, as well as cultured Schwann cells. RESULTS: Injection treatment resulted in larger volumes and a more uniform cross-sectional distribution of implanted cells. Beads and cells behaved similarly relative to the measured outcomes. CONCLUSIONS: Injection instills more cells in a more uniform distribution. In vivo testing may evaluate whether these techniques vary relative to cell survival, cell migration, and clinical outcomes. Size- and concentration-matched fluorescent beads may represent a viable model for analyzing cell implantation.

Which mesh or graft? Prosthetic devices for abdominal wall reconstruction.

This article reviews the ever-increasing number of prosthetic devices--both synthetic mesh and biologic grafts--now in use for abdominal wall reconstruction. It also introduces a novel hybrid synthetic/biologic graft (Zenapro) and suture passer device (Novapass).

Autologous Fat Grafting to the Breast Using REVOLVE System to Reduce Clinical Costs.

BACKGROUND: With the increasing popularity of fat grafting over the past decade, the techniques for harvest, processing and preparation, and transfer of the fat cells have evolved to improve efficiency and consistency. The REVOLVE System is a fat processing device used in autologous fat grafting which eliminates much of the specialized equipment as well as the labor intensive and time consuming efforts of the original Coleman technique of fat processing. This retrospective study evaluates the economics of fat grafting, comparing traditional Coleman processing to the REVOLVE System. METHODS: From June 2013 through December 2013, 88 fat grafting cases by a single-surgeon were reviewed. Timed procedures using either the REVOLVE System or Coleman technique were extracted from the group. Data including fat grafting procedure time, harvested volume, harvest and recipient sites, and concurrent procedures were gathered. Cost and utilization assessments were performed comparing the economics between the groups using standard values of operating room costs provided by the study hospital. RESULTS: Thirty-seven patients with timed procedures were identified, 13 of which were Coleman technique patients and twenty-four (24) were REVOLVE System patients. The average rate of fat transfer was 1.77 mL/minute for the Coleman technique and 4.69 mL/minute for the REVOLVE System, which was a statistically significant difference (P < 0.0001) between the 2 groups. Cost analysis comparing the REVOLVE System and Coleman techniques demonstrates a dramatic divergence in the price per mL of transferred fat at 75 mL when using the previously calculated rates for each group. CONCLUSIONS: This single surgeon's experience with the REVOLVE System for fat processing establishes economic support for its use in specific high-volume fat grafting cases. Cost analysis comparing the REVOLVE System and Coleman techniques suggests that in cases of planned fat transfer of 75 mL or more, using the REVOLVE System for fat processing is more economically beneficial. This study may serve as a guide to plastic surgeons in deciding which cases might be appropriate for the use of the REVOLVE System and is the first report comparing economics of fat grafting with the traditional Coleman technique and the REVOLVE System.

Standardized DMEK Technique: Reducing Complications Using Prestripped Tissue, Novel Glass Injector, and Sulfur Hexafluoride (SF6) Gas.

PURPOSE: To report low complication rates in Descemet membrane endothelial keratoplasty (DMEK) using sulfur hexafluoride (SF6) gas, a novel glass injector, and donor tissue prestripped by an eye bank technician. METHODS: A standardized technique of DMEK was performed in 80 consecutive Fuchs corneal dystrophy cases using technician-prestripped tissue, a novel glass injector, a modified Yoeruek tap technique, and an SF6 gas (20% concentration) bubble for prolonged tissue support. Twenty-five donors were premarked with an "S" stamp for intraoperative orientation. Surgery was performed by 2 experienced DMEK surgeons and 2 inexperienced cornea fellows. Complications were recorded, and the percent endothelial cell loss was calculated at 6 months postoperatively. RESULTS: There were 5 cases that received an air bubble injection postoperatively (6% rebubble rate). There were 6 grafts that immediately failed, 2 because of excessive surgical trauma, and 4 because of upside-down graft placement documented by optical coherence tomography. None of the 25 cases with an S stamp failed. Recipient corneas cleared quickly with no clinical evidence of toxicity from the SF6 gas bubble, and the grafts experienced a mean endothelial cell loss of 27% at 6 months. CONCLUSIONS: Tissue prestripped by an eye bank technician can be safely used for DMEK surgery. SF6 gas for prolonged tissue support may reduce the rebubble rate in DMEK, with no apparent acute toxic effect. An unrecognized upside-down graft was the primary cause of graft failure in this series. Upside-down grafts may be eliminated by the use of donor tissue premarked by the eye bank with an S orientation stamp.

Precise and rapid costal cartilage graft sectioning using a novel device: clinical application.

IMPORTANCE The use of costal cartilage as a graft in facial reconstructive surgery requires sectioning the cartilage into a suitable shape. OBJECTIVE To evaluate the accuracy of a novel mechanical device for producing uniform slices of costal cartilage and to illustrate the use of the device during nasal surgery. DESIGN Basic and clinical study using 100 porcine ex vivo costal cartilage slices and 9 operative cases. METHODS This instrument departs from antecedent devices in that it uses compression to secure and stabilize the specimen during sectioning. A total of 75 porcine costal cartilage ribs were clamped with minimal compression just sufficient to secure and stabilize the specimen while cutting. Slices having a length of 4 cm and width of 1 cm were obtained using the cartilage cutter at 3 thicknesses: 1 mm (n = 25), 2 mm (n = 25), and 3 mm (n = 25). The procedure was repeated for the 2-mm thick samples; however, the ribs in this group (n = 25) were clamped using the maximum amount of compression attainable by the device. Thickness was measured using a digital micrometer. Case presentations illustrate the use of the device in secondary and reconstructive rhinoplasty surgery. RESULTS All specimens were highly uniform in thickness on visual inspection and appeared to be adequate for clinical application. Sectioning was completed in several seconds without complication. In the porcine specimens sectioned using minimal compression, the percentage difference in thickness for each individual sample averaged 18%, 10%, and 11% for the 1-mm-, 2-mm-, and 3-mm-thick slices, respectively. Within the specimens sectioned using maximum compression, the percentage difference in thickness for each individual sample averaged 35% for the 2-mm-thick slices. In the setting of nasal reconstructive surgery, slices having a thickness from 1 to 2 mm were found to be well suited for all necessary graft types. CONCLUSIONS AND RELEVANCE The simple mechanical device described produces costal cartilage graft slices with highly uniform thickness. Securing the rib by clamping during cutting reduces uniformity of the slices; however, the imperfections are minimal, and all sectioned grafts are adequate for clinical application. The device can be adjusted to produce slices of appropriate thickness for all nasal cartilage grafts. This device is valuable for reconstructive procedures owing to its ease of use, rapid operation, and reproducible results.

Transplantation of neural tissue: quail-chick chimeras.

Tissue transplantation is an important approach in developmental neurobiology to determine cell fate, to uncover inductive interactions required for tissue specification and patterning as well as to establish tissue competence and commitment. Avian species are among the favorite model systems for these approaches because of their accessibility and relatively large size. Here we describe two culture techniques used to generate quail-chick chimeras at different embryonic stages and methods to distinguish graft and donor tissue.

A classification of clinical fat grafting: different problems, different solutions.

BACKGROUND: Fat grafting has reemerged from a highly variable procedure to a technique with vast reconstructive and cosmetic potential. Largely because of a more disciplined and scientific approach to fat grafting as a transplantation event, early adopters of fat transplantation have begun to approach fat grafting as a process, using sound surgical transplantation principles: recipient preparation, controlled donor harvest, time-efficient transplantation, and proper postoperative care. Despite these principles, different fat grafting techniques yield impressive clinical outcomes. METHODS: The essential variables of four types of fat grafting cases were identified and compared: harvesting, methods of cell processing, methods of transplantation, and management of the recipient site. RESULTS: Each case differed for most of the variables analyzed. The two clinical drivers that most impacted these differences were the volume demands of the recipient site and whether the recipient site was healthy tissue or pathologic tissue. After these two drivers, a matrix classification of small-volume versus large-volume and regenerative versus nonregenerative cases yields four distinct categories. CONCLUSIONS: Not all fat grafting is the same. Fat grafting, once thought to be a simple technique with variable results, is a much more complex procedure with at least four definable subtypes. By defining the essential differences in the recipient site, the key driver in fat transplantation, the proper selection of technique can be best chosen. In fat transplantation, different problems require different solutions.

Surrogate human tissue temperatures resulting from misalignment of antenna and implant during recharging of a neuromodulation device.

OBJECTIVES: A synergistic experimental and numerical investigation has provided quantitative information on the response of surrogate human tissue temperatures to misalignment of the implant and antenna of neuromodulation devices during recharging. MATERIALS AND METHODS: The experimental phase of the work provided information on the rates of heat transfer from the implant and the antenna to their respective surroundings. The heat transfer data were used as input to a biothermal model from which tissue temperature distributions were obtained. RESULTS: It was found that misalignment increases tissue temperatures compared with those for the aligned case for all of the investigated devices. These increases ranged from 0.5°C to 5.3°C. CONCLUSION: Notwithstanding these increases, the lowest temperatures were attained by the Restore Ultra device for all operating conditions. The temperature levels achieved by the Precision Plus and Eon Mini devices were found to be greater than those for the Restore Ultra but their relative rankings depend on the thermal boundary conditions and the duration of the recharging period. The foregoing rank ordering was validated by a sensitivity study in which the heat transfer data inputted to the numerical simulation was varied systematically. The aforementioned comparisons correspond with identical recharging periods for all of the devices.

Cost analysis of outpatient anterior cruciate ligament reconstruction: autograft versus allograft.

BACKGROUND: Prior studies suggest the cost of allograft anterior cruciate ligament (ACL) reconstruction is less than that for autograft reconstruction. Charges in these studies were influenced by patients requiring inpatient hospitalization. QUESTION/PURPOSE: We therefore determined if allograft ACL reconstruction would still be less costly if all procedures were performed in a completely outpatient setting. METHODS: We retrospectively reviewed 155 patients who underwent ACL reconstruction in an ambulatory surgery center between 2001 and 2004; 105 had an autograft and 50 had an allograft. Charges were extracted from itemized billing records, standardized to eliminate cost increases, and categorized for comparison. Surgeon and anesthesiologist fees were not included in the analysis. Groups were compared for age, gender, mean total cost, mean cost of implants, and several other cost categories. RESULTS: The mean total cost was $5465 for allograft ACL reconstruction and $4872 for autograft ACL reconstruction. There were no differences in complications between the two groups. CONCLUSIONS: Allograft ACL reconstruction was more costly than autograft ACL reconstruction in the outpatient setting. The cost of the allograft outweighs the increased surgical time needed for harvesting an autograft. LEVEL OF EVIDENCE: Level II, economic and decision analyses. See Guidelines for Authors for a complete description of levels of evidence.