Objective:To establish a three-dimensional finite element model of the nose, simulate and analyze the deformation of nasal tissue caused by different focal points, traction directions, and modes, provide the theoretical basis for the effectiveness of physical traction therapy, and guide the clinical selection of more efficient physical traction therapy methods.Methods:A finite element model of the nose was established by ANSYS Workbench 19.2 software based on image data obtained from CT scans of a 29-year-old male volunteer with normal nasal appearance in Peking University Third Hospital. Two focal points, the nasal tip, and the nasal columella, were selected, and three force directions, parallel to the forward, forward and down 30°, forward and down 60°, were applied. The deformation caused by different traction conditions on the skin, lining, and soft bone parts, as well as the four anatomical landmarks of the nasal tip, nasal root, the midpoint of the nasal columella, and the nasal base, were compared. The deformation produced by 10 minutes of continuous pulling and 10 times 1-minute pulse pulling were compared under the same pulling conditions. The deformations generated by two types of pulling modes within a 24-hour cycle: a single 1-hour cycle and 6 intermittent 10-minute cycles, were compared.Results:All traction conditions resulted in deformation of the nasal model, with the maximum deformation of the nasal tissue obtained by pulling forward and downward at 60° (4.632 9 mm) which was greater than other traction conditions (0.825 0-3.105 0 mm). The maximum deformation value was located near the nasion of the model’s skin layer. The deformation obtained by 10 minutes of continuous pulling (0.176 6 mm) was slightly greater than that obtained by 10 times of 1-minute pulse pulling (0.176 5 mm). Within 24 hours, the final deformation of multiple intermittent pulling modes (0.019 0 mm) was greater than that of a single pulling mode (0.004 3 mm).Conclusion:Physical traction can effectively deform the skin and soft tissue of the nose, and the most efficient operation is to continuously pinch the tip of the nose for a short period and apply tension parallel to the back of the nose downwards, repeating every a few hours.

Objective:To investigate the clinical effect of autologous fat transplantation combined with hair transplantation in the treatment of hard and/or thin scalp flat scar after burn.Methods:The clinical data of patients with hard and thin scalp scar after burn admitted to the Department of Plastic Surgery of Peking University Third Hospital from January 2017 to December 2022 were retrospectively analyzed. Fat was extracted from the lower abdomen or outer thigh during the operation, and then injected into the scalp scar after standing for 15 minutes, about 0.8 ml/cm 2 under the hard and/or thin scar area, and 0.2-0.4 ml/cm 2 under the thick and soft scar area. Three months after fat transplantation, hair transplantation was performed in the scar bald area, and the transplant density was 25-35 follicular units (FUs)/cm 2 in the hard and thin scar area, and 30-40 FUs /cm 2 in the thick and soft scar area. The Vancouver scar scale (VSS) was used by two third party plastic surgeons to score the hard and/or thin scar areas of the scalp before and 3 months after scalp fat transplantation. The VSS score was expressed as M ( Q1, Q3), and the preoperative and postoperative data were compared by paired sample Wilcoxon signed rank test. During hair transplantation, the density of implanted hair in the hard and/or thin scar area were recorded. The density of living hair at these sites was measured at the last follow-up, and then the survival rate of hair (living hair density/implant hair density ×100%) was calculated. A third party plastic surgeon evaluated the extent to which scalp scars in the hair transplant area were covered, including completely covered, basically covered, partially covered. Patients’ evaluation with the surgical result was divided into very satisfied, satisfied and dissatisfied. Results:A total of 57 patients with scalp scar after burn were included in this group, including 31 males and 26 females, aged 13-47 years old. The time from scalp scarring to treatment was 8-41 years. The area of scalp scar was 17-120 cm 2, with an average of 63.3 cm 2. The fat injection volume of 57 patients was 13-75 ml. The hair transplantation was performed 3-8 months after a single fat filling procedure. The total amount of hair transplantation was 510-3 120 FUs. The total score of postoperative scar VSS was 4(3, 4), significantly lower than the preoperative score of 7(6, 7) ( W=6.70, P < 0.001). The color, thickness, blood vessel distribution and softness were significantly reduced compared with those before surgery ( P< 0.01). All patients were followed up for 12-18 months (mean, 14 months) after hair transplantation. The survival rate of hair in hard and thin scar area was 68.2% (22.7 FUs/cm 2/33.3 FUs/cm 2) to 89.7% (26.1 FUs/cm 2/29.1 FUs/cm 2), with an average of 81.3%. In 32 patients, scalp scars were completely covered. The scalp scar of 25 patients was basically covered. Twenty-nine patients were very satisfied with the result of the operation, and 28 patients were satisfied. Conclusion:The high survival rate of hair transplantation can be obtained by injecting fat under the hard and/or thin scalp scars before hair transplantation, which is an effective method to repair scalp scars.

Objective:To investigate the effectiveness of new cryoprotective agents in preserving and transplanting human adipose tissue.Methods:The adipose tissue samples were obtained from healthy adult females who underwent liposuction at the Department of Plastic Surgery of Peking University Third Hospital from January to March 2022. The adipose tissue samples were centrifuged and then randomly divided into 9 groups. These groups were cryopreserved in liquid nitrogen using different cryoprotective agents [group A, group B, and dimethyl sulfoxide (DMSO) group] and cryopreservation times (1-month, 2-month, and 3-month groups), respectively. The cryoprotective agent formulation in group A was dextrose glycoside 40 (DEX), amino acids, vitamins, and inorganic salts. In group B, the formulation included DMSO and DEX. The ratio of cryoprotective agent in the DMSO group was 10% DMSO, 20% fetal bovine serum (FBS), and 70% DMEM-12. For cryopreservation, 5 ml cryogenic tubes were used with a fat to cryoprotective agent ratio of 3∶2, and each group contains 6 tubes for cryopreservation. After thawing the adipose tissue, HE staining was used to observe the histological morphology. Immunohistochemical staining was employed for the quantitative analysis of lipid droplet-encapsulated protein (Perilipin), and the Perilipin positivity rate was calculated by the ratio of the number of positive cells to the total number of cells. Adipocyte viability was assessed using the CCK-8 method. Thirty-eight healthy, clean nude mice were selected and divided into 3 groups of 12 mice each according to the use of different cryoprotective agents (groups A, B, and DMSO), while the other 2 mice were used as the day 0 control group. The mean fat freezing duration for all groups was 3 months. After nude mice were anesthetized intraperitoneally, 0.9 ml of thawed cryopreserved fat was injected into the dorsum bilaterally. The rate of adipose tissue retention was calculated by MRI scanning and three-dimensional software at 1, 2, and 3 months after transplantation, and compared between the groups. The fat grafts were explanted from the mice after they were sacrificed, and then subjected to histological morphology and quantitative analysis of Perilipin by using HE staining and immunohistochemical staining. GraphPad Prism 8.0 software was used for statistical analysis of the data. The data that conformed to a normal distribution were expressed as Mean ± SD. The overall comparison between multiple groups used analysis of variance for repeated measures. The comparison of data between groups at the same time point used Tukey’s multiple comparison test.Results:The morphology of adipose tissue in different cryoprotective agent groups closely resembled that of normal fresh adipose tissue after being cryopreserved in liquid nitrogen for 1-3 months. The difference in the proportion of Perilipin-stained positive cells in each group was not statistically significant ( P>0.05). The CCK-8 method indicated that the effect of the DMSO group was superior to groups A and B at 1 and 3 months of cryopreservation ( P<0.01), and that the DMSO group and group B were superior to group A at 2 months of cryopreservation ( P<0.01). In the animal experiments, there was no statistically significant difference between the groups in the volume retention rate 1-3 months after cryopreserved fat transplantation ( P>0.05). Additionally, the adipose tissues in each group exhibited varying degrees of localized necrosis accompanied by an inflammatory reaction 1-3 months after transplantation. There was no statistically significant difference in the Perilipin staining positivity between the groups ( P>0.05). Conclusion:The use of new cryoprotective agents for cryopreserving adipose tissue does not show a significant difference compared to the traditional cryoprotective agent. However, it is theoretically safer as it avoids the potential toxic effects of using DMSO or FBS on the human body.

Objective:To investigate the clinical effect of autologous fat transplantation combined with hair transplantation in the treatment of hard and/or thin scalp flat scar after burn.Methods:The clinical data of patients with hard and thin scalp scar after burn admitted to the Department of Plastic Surgery of Peking University Third Hospital from January 2017 to December 2022 were retrospectively analyzed. Fat was extracted from the lower abdomen or outer thigh during the operation, and then injected into the scalp scar after standing for 15 minutes, about 0.8 ml/cm 2 under the hard and/or thin scar area, and 0.2-0.4 ml/cm 2 under the thick and soft scar area. Three months after fat transplantation, hair transplantation was performed in the scar bald area, and the transplant density was 25-35 follicular units (FUs)/cm 2 in the hard and thin scar area, and 30-40 FUs /cm 2 in the thick and soft scar area. The Vancouver scar scale (VSS) was used by two third party plastic surgeons to score the hard and/or thin scar areas of the scalp before and 3 months after scalp fat transplantation. The VSS score was expressed as M ( Q1, Q3), and the preoperative and postoperative data were compared by paired sample Wilcoxon signed rank test. During hair transplantation, the density of implanted hair in the hard and/or thin scar area were recorded. The density of living hair at these sites was measured at the last follow-up, and then the survival rate of hair (living hair density/implant hair density ×100%) was calculated. A third party plastic surgeon evaluated the extent to which scalp scars in the hair transplant area were covered, including completely covered, basically covered, partially covered. Patients’ evaluation with the surgical result was divided into very satisfied, satisfied and dissatisfied. Results:A total of 57 patients with scalp scar after burn were included in this group, including 31 males and 26 females, aged 13-47 years old. The time from scalp scarring to treatment was 8-41 years. The area of scalp scar was 17-120 cm 2, with an average of 63.3 cm 2. The fat injection volume of 57 patients was 13-75 ml. The hair transplantation was performed 3-8 months after a single fat filling procedure. The total amount of hair transplantation was 510-3 120 FUs. The total score of postoperative scar VSS was 4(3, 4), significantly lower than the preoperative score of 7(6, 7) ( W=6.70, P < 0.001). The color, thickness, blood vessel distribution and softness were significantly reduced compared with those before surgery ( P< 0.01). All patients were followed up for 12-18 months (mean, 14 months) after hair transplantation. The survival rate of hair in hard and thin scar area was 68.2% (22.7 FUs/cm 2/33.3 FUs/cm 2) to 89.7% (26.1 FUs/cm 2/29.1 FUs/cm 2), with an average of 81.3%. In 32 patients, scalp scars were completely covered. The scalp scar of 25 patients was basically covered. Twenty-nine patients were very satisfied with the result of the operation, and 28 patients were satisfied. Conclusion:The high survival rate of hair transplantation can be obtained by injecting fat under the hard and/or thin scalp scars before hair transplantation, which is an effective method to repair scalp scars.

Objective:To investigate the effectiveness of new cryoprotective agents in preserving and transplanting human adipose tissue.Methods:The adipose tissue samples were obtained from healthy adult females who underwent liposuction at the Department of Plastic Surgery of Peking University Third Hospital from January to March 2022. The adipose tissue samples were centrifuged and then randomly divided into 9 groups. These groups were cryopreserved in liquid nitrogen using different cryoprotective agents [group A, group B, and dimethyl sulfoxide (DMSO) group] and cryopreservation times (1-month, 2-month, and 3-month groups), respectively. The cryoprotective agent formulation in group A was dextrose glycoside 40 (DEX), amino acids, vitamins, and inorganic salts. In group B, the formulation included DMSO and DEX. The ratio of cryoprotective agent in the DMSO group was 10% DMSO, 20% fetal bovine serum (FBS), and 70% DMEM-12. For cryopreservation, 5 ml cryogenic tubes were used with a fat to cryoprotective agent ratio of 3∶2, and each group contains 6 tubes for cryopreservation. After thawing the adipose tissue, HE staining was used to observe the histological morphology. Immunohistochemical staining was employed for the quantitative analysis of lipid droplet-encapsulated protein (Perilipin), and the Perilipin positivity rate was calculated by the ratio of the number of positive cells to the total number of cells. Adipocyte viability was assessed using the CCK-8 method. Thirty-eight healthy, clean nude mice were selected and divided into 3 groups of 12 mice each according to the use of different cryoprotective agents (groups A, B, and DMSO), while the other 2 mice were used as the day 0 control group. The mean fat freezing duration for all groups was 3 months. After nude mice were anesthetized intraperitoneally, 0.9 ml of thawed cryopreserved fat was injected into the dorsum bilaterally. The rate of adipose tissue retention was calculated by MRI scanning and three-dimensional software at 1, 2, and 3 months after transplantation, and compared between the groups. The fat grafts were explanted from the mice after they were sacrificed, and then subjected to histological morphology and quantitative analysis of Perilipin by using HE staining and immunohistochemical staining. GraphPad Prism 8.0 software was used for statistical analysis of the data. The data that conformed to a normal distribution were expressed as Mean ± SD. The overall comparison between multiple groups used analysis of variance for repeated measures. The comparison of data between groups at the same time point used Tukey’s multiple comparison test.Results:The morphology of adipose tissue in different cryoprotective agent groups closely resembled that of normal fresh adipose tissue after being cryopreserved in liquid nitrogen for 1-3 months. The difference in the proportion of Perilipin-stained positive cells in each group was not statistically significant ( P>0.05). The CCK-8 method indicated that the effect of the DMSO group was superior to groups A and B at 1 and 3 months of cryopreservation ( P<0.01), and that the DMSO group and group B were superior to group A at 2 months of cryopreservation ( P<0.01). In the animal experiments, there was no statistically significant difference between the groups in the volume retention rate 1-3 months after cryopreserved fat transplantation ( P>0.05). Additionally, the adipose tissues in each group exhibited varying degrees of localized necrosis accompanied by an inflammatory reaction 1-3 months after transplantation. There was no statistically significant difference in the Perilipin staining positivity between the groups ( P>0.05). Conclusion:The use of new cryoprotective agents for cryopreserving adipose tissue does not show a significant difference compared to the traditional cryoprotective agent. However, it is theoretically safer as it avoids the potential toxic effects of using DMSO or FBS on the human body.

Objective:To establish a three-dimensional finite element model of the nose, simulate and analyze the deformation of nasal tissue caused by different focal points, traction directions, and modes, provide the theoretical basis for the effectiveness of physical traction therapy, and guide the clinical selection of more efficient physical traction therapy methods.Methods:A finite element model of the nose was established by ANSYS Workbench 19.2 software based on image data obtained from CT scans of a 29-year-old male volunteer with normal nasal appearance in Peking University Third Hospital. Two focal points, the nasal tip, and the nasal columella, were selected, and three force directions, parallel to the forward, forward and down 30°, forward and down 60°, were applied. The deformation caused by different traction conditions on the skin, lining, and soft bone parts, as well as the four anatomical landmarks of the nasal tip, nasal root, the midpoint of the nasal columella, and the nasal base, were compared. The deformation produced by 10 minutes of continuous pulling and 10 times 1-minute pulse pulling were compared under the same pulling conditions. The deformations generated by two types of pulling modes within a 24-hour cycle: a single 1-hour cycle and 6 intermittent 10-minute cycles, were compared.Results:All traction conditions resulted in deformation of the nasal model, with the maximum deformation of the nasal tissue obtained by pulling forward and downward at 60° (4.632 9 mm) which was greater than other traction conditions (0.825 0-3.105 0 mm). The maximum deformation value was located near the nasion of the model’s skin layer. The deformation obtained by 10 minutes of continuous pulling (0.176 6 mm) was slightly greater than that obtained by 10 times of 1-minute pulse pulling (0.176 5 mm). Within 24 hours, the final deformation of multiple intermittent pulling modes (0.019 0 mm) was greater than that of a single pulling mode (0.004 3 mm).Conclusion:Physical traction can effectively deform the skin and soft tissue of the nose, and the most efficient operation is to continuously pinch the tip of the nose for a short period and apply tension parallel to the back of the nose downwards, repeating every a few hours.

In the field of plastic and reconstructive surgery, the loss of organs or tissues caused by diseases or injuries has resulted in challenges, such as donor shortage and immunosuppression. In recent years, with the development of regenerative medicine, the decellularization-recellularization strategy seems to be a promising and attractive method to resolve these difficulties. The decellularized extracellular matrix contains no cells and genetic materials, while retaining the complex ultrastructure, and it can be used as a scaffold for cell seeding and subsequent transplantation, thereby promoting the regeneration of diseased or damaged tissues and organs. This review provided an overview of decellularization-recellularization technique, and mainly concentrated on the application of decellularization-recellularization technique in the field of plastic and reconstructive surgery, including the remodeling of skin, nose, ears, face, and limbs. Finally, we proposed the challenges in and the direction of future development of decellularization-recellularization technique in plastic surgery.
Tissue Engineering/methods* ; Tissue Scaffolds/chemistry* ; Surgery, Plastic ; Regenerative Medicine/methods* ; Extracellular Matrix

BACKGROUND: The phenotype maintenance of diced cartilage is a very important factor to reduce cartilage absorption rate in augmentation rhinoplasty. A novel method which combined diced cartilage with chondrocyte spheroids in gelatin methacrylate (GelMA) hydrogel may have potentially good performance in phenotype maintenance, and is worth exploring. METHODS: The complex grafts formed by loading diced cartilage with chondrocyte spheroids into GelMA hydrogel were used as the experimental group, and the grafts formed of diced cartilage in GelMA were used as the control group.The two groups of grafts were implanted subcutaneously in nude mice. After 1 month and 3 months, the grafts were taken for general observation and histological analysis. The diameter changes of cartilage, the nuclei loss of chondrocyte, and glycosaminoglycan secretion were analyzed. RESULTS: Chondrocyte spheroids with obvious proliferation can be seen in the experimental group. Some diced cartilages had become a whole through the interconnection of chondrocyte spheroids. In addition, the diameter of the chondrocyte spheroids—diced cartilage complex in the experimental group increased significantly, and its nuclei loss rate was less than 1/2 of that in the control group. The maintenance of proteoglycans in diced cartilages in the experimental group was significantly better than that in the control group. CONCLUSION The combination of diced cartilage with chondrocyte spheroids in GelMA hydrogel can significantly reduce the absorption of cartilage extracellular matrix, enhance phenotype maintenance during subcutaneous ectopic implantation, and can produce inter-chondral connections.

Adipocytes ; Adipose Tissue ; Exosomes ; Stem Cells ; Wound Healing

BACKGROUND: As a contour-supporting material, the cartilage has a significant application value in plastic surgery.Since the development of hydrogel scaffolds with sufficient biomechanical strength and high biocompatibility, cell-laden hydrogels have been widely studied for application in cartilage bioengineering. This systematic review summarizes the latest research on engineered cartilage constructed using cell-laden hydrogel scaffolds in plastic surgery. METHODS: A systematic review was performed by searching the PubMed and Web of Science databases using selected keywords and Medical Subject Headings search terms. RESULTS: Forty-two studies were identified based on the search criteria. After full-text screening for inclusion and exclusion criteria, 18 studies were included. Data collected from each study included culturing form, seed cell types and sources, concentration of cells and gels, scaffold materials and bio-printing structures, and biomechanical properties of cartilage constructs. These cell-laden hydrogel scaffolds were reported to show some feasibility of cartilage engineering, including better cell proliferation, enhanced deposition of glycosaminoglycans and collagen type II in the extracellular matrix, and better biomechanical properties close to the natural state. CONCLUSION Cell-laden hydrogels have been widely used in cartilage bioengineering research. Through 3-dimensional (3D) printing, the cell-laden hydrogel can form a bionic contour structure. Extracellular matrix expression was observed in vivo and in vitro, and the elastic modulus was reported to be similar to that of natural cartilage. The future direction of cartilage tissue engineering in plastic surgery involves the use of novel hydrogel materials and more advanced 3D printing technology combined with biochemistry and biomechanical stimulation.