Distribution of pathogens and risk factors for post-replantation wound infection in patients with traumatic major limb mutilation.

PURPOSE: Even though replantation of limb mutilation is increasing, postoperative wound infection can result in increasing the financial and psychological burden of patients. Here, we sought to explore the distribution of pathogens and identify risk factors for postoperative wound infection to help early identification and managements of high-risk patients. METHODS: Adult inpatients with severed traumatic major limb mutilation who underwent replantation from Suzhou Ruixing Medical Group between November 09, 2014, and September 6, 2022 were included in this retrospective study. Demographic, and clinical characteristics, treatments, and outcomes were collected. Data were used to analyze risk factors for postoperative wound infection. RESULTS: Among the 249 patients, 185 (74.3%) were males, the median age was 47.0 years old. Postoperative wound infection in 74 (29.7%) patients, of whom 51 (20.5%) had infection with multi-drug resistant bacteria. Ischemia time (OR 1.31, 95% CI 1.13-1.53, P = 0.001), wound contamination (OR 6.01, 95% CI 2.38-15.19, P <0.001), and stress hyperglycemia (OR 23.37, 95% CI 2.30-236.93, P = 0.008) were independent risk factors, while the albumin level after surgery (OR 0.94, 95% CI 0.89-0.99, P = 0.031) was significant associated with the decrease of postoperative wound infection. Ischemia time (OR 1.21, 95% CI 1.05-1.40, P = 0.010), wound contamination (OR 8.63, 95% CI 2.91-25.57, P <0.001), and MESS (OR 1.32, 95% CI 1.02-1.71, P = 0.037 were independent risk factors for multi-drug resistant bacteria infection. CONCLUSIONS: Post-replantation wound infection was common in patients with severe traumatic major limb mutilation, and most were multi-drug resistant bacteria. Ischemia time and wound contamination were associated with the increase of postoperative wound infection, including caused by multi-drug resistant. Positive correction of hypoproteinemia and control of stress hyperglycemia may be beneficial.

Comparative Study of the Morphological Characteristics of Perforators of the Transverse and Descending Branches of the Lateral Circumflex Femoral Artery in Anterolateral Thigh Flap Surgery.

BACKGROUND: The anterolateral thigh flap (ALTF) is a kind of lateral thigh flap that uses branches of the lateral circumflex femoral artery (LCFA) as the vessel pedicle and is widely used in plastic surgery. During classic ALTF surgery, some perforators from the descending branch of the lateral circumflex femoral artery (LCFA-db) are hard to harvest due to their anatomical variants and individual differences; thus, it is necessary to design an appropriate alternative surgical plan. The transverse branch of the LCFA (LCFA-tb) has unique advantages and can be a potential complement to ALTF vascular pedicle selection. The aim of this study was to compare the difference in morphology between LCFA-db and LCFA-tb, and to verify the feasibility and clinical effect of ALTF with LCFA-tb as the source artery. METHODS: The morphological and clinical data of patients who underwent wound repair of the extremities with the ALTF pedicled with the LCFA-tb and LCFA-db were retrospectively analyzed. This study consisted of the clinical data of 62 patients who accepted an ALTF pedicled with LCFA-tb, and 45 patients accepted an ALTF pedicled with LCFA-db. RESULTS: A total of 68 cutaneous perforators originating from the LCFA-tb were found in the surgical field, of which 35 perforators were direct cutaneous perforators (51.5%), 28 perforators were septocutaneous perforators (41.2%), and 5 perforators were musculocutaneous perforators (7.3%). Seventy-four cutaneous perforators were found in the LCFA-db group. The proportions of septocutaneous perforators and musculocutaneous perforators were 23% and 77%, respectively, and the number of direct cutaneous perforators was 0. The harvest time of flaps pedicled with LCFA-tb was remarkably shortened. Regarding prognosis, there were no significant differences between the curative effects of the 2 types of flaps. CONCLUSIONS: This study verified that most LCFA-tb perforators are direct cutaneous perforators and that the piercing-in positions of LCFA-tb perforators on superficial fascia were higher than those of LCFA-db perforators. Furthermore, the ALTF pedicled with LCFA-tb can provide satisfactory soft tissue reconstruction and can be used as a useful supplement to the traditional flap design.

Bioprinted dermis with human adipose tissue-derived microvascular fragments promotes wound healing.

Tissue-engineered skin is an effective material for treating large skin defects in a clinical setting. However, its use is limited owing to vascular complications. Human adipose tissue-derived microvascular fragments (HaMVFs) are vascularized units that form vascular networks by rapid reassembly. In this study, we designed a vascularized bionic skin tissue using a three-dimensional (3D) bioprinter of HaMVFs and human fibroblasts encapsulated in a hybrid hydrogel composed of GelMA, HAMA, and fibrinogen. Tissues incorporating HaMVFs showed good in vitro vascularization and mechanical properties after UV crosslinking and thrombin exposure. Thus, the tissue could be sutured appropriately to the wound. In vivo, the vascularized 3D bioprinted skin promoted epidermal regeneration, collagen maturation in the dermal tissue, and vascularization of the skin tissue to accelerate wound healing. Overall, vascularized 3D bioprinted skin with HaMVFs is an effective material for treating skin defects and may be clinically applicable to reduce the necrosis rate of skin grafts.

Engineered dermis loaded with confining forces promotes full-thickness wound healing by enhancing vascularisation and epithelialisation.

Tissue-engineered skin is ideal for clinical wound repair. Restoration of skin tissue defects using tissue-engineered skin remains a challenge owing to insufficient vascularisation. In our previous study, we developed a 3D bioprinted model with confined force loading and demonstrated that the confined force can affect vascular branching, which is regulated by the YAP signalling pathway. The mechanical properties of the model must be optimised to suture the wound edges. In this study, we explored the ability of a GelMA-HAMA-fibrin scaffold to support the confined forces created by 3D bioprinting and promote vascularisation and wound healing. The shape of the GelMA-HAMA-fibrin scaffold containing 3% GelMA was affected by the confined forces produced by the embedded cells. The GelMA-HAMA-fibrin scaffold was easy to print, had optimal mechanical properties, and was biocompatible. The constructs were successfully sutured together after 14 d of culture. Scaffolds seeded with cells were transplanted into skin tissue defects in nude mice, demonstrating that the cell-seeded GelMA-HAMA-fibrin scaffold, under confined force loading, promoted neovascularisation and wound restoration by enhancing blood vessel connections, creating a patterned surface, growth factors, and collagen deposition. These results provide further insights into the production of hydrogel composite materials as tissue-engineered scaffolds under an internal mechanical load that can enhance vascularisation and offer new treatment methods for wound healing. STATEMENT OF SIGNIFICANCE: Tissue-engineered skin is ideal for use in clinical wound repair. However, treatment of tissue defects using synthetic scaffolds remains challenging, mainly due to slow and insufficient vascularization. Our previous study developed a 3D bioprinted model with confined force loading, and demonstrated that confined force can affect vascular branching regulated by the YAP signal pathway. The mechanical properties of the construct need to be optimized for suturing to the edges of wounds. Here, we investigated the ability of a GelMA-HAMA-fibrin scaffold to support the confined forces created by 3D bioprinting and promote vascularization in vitro and wound healing in vivo. Our findings provide new insight into the development of degradable macroporous composite materials with mechanical stimulation as tissue-engineered scaffolds with enhanced vascularization, and also provide new treatment options for wound healing.

Reconstruction of large-area wounds in limbs using two flow-through anterolateral thigh perforator flaps.

INTRODUCTION: Limb salvage in large wounds is difficult because the disrupted blood supply does not support a flap. This study evaluated the clinical efficacy of using two flow-through anterolateral thigh perforator flaps for reconstructing large-area limb wounds. METHODS: This retrospective study included 45 patients who underwent reconstruction of large limb wounds using two flow-through anterolateral thigh perforator flaps at Ruihua Hospital between January 2015 and December 2020. Wound areas ranged from 15 cm × 13 cm to 46 cm × 18 cm. Single flap areas ranged from 16 cm × 8 cm to 46 cm × 9 cm. Blood supply locations were identified using color Doppler ultrasound or digital subtraction angiography (DSA) images. Primary outcomes were flap survival and complications at recipient or donor sites during at least 6-months follow-up. RESULTS: The overall flap survival rate was 97% (87/90). All donor sites healed by first intention. Three cases developed vascular crises, which were alleviated by reoperation. One case had flexor contracture in left toes, relieved by cutting flexor tendons; 13 cases had flap bloat, relieved by flap thinning at 6 months. All cases showed properly healed wounds and functional reconstruction. CONCLUSIONS: Reconstruction of large-area limb wounds using two flow-through anterolateral thigh perforator flaps provides safe and satisfactory effects without donor-site morbidity, and with proper healing and restored function.

Angiopoietin-like 4 promotes epidermal stem cell proliferation and migration and contributes to cutaneous wound re-epithelialization.

Proliferation and migration of epidermal stem cells (EpSCs) are essential for epithelialization during skin wound healing. Angiopoietin-like 4 (ANGPTL4) has been reported to play an important role in wound healing, but the mechanisms involved are not fully understood. Here, we investigate the contribution of ANGPTL4 to full-thickness wound re-epithelialization and the underlying mechanisms using Angptl4-knockout mice. Immunohistochemical staining reveals that ANGPTL4 is significantly upregulated in the basal layer cells of the epidermis around the wound during cutaneous wound healing. ANGPTL4 deficiency impairs wound healing. H&E staining shows that ANGPTL4 deficiency significantly reduces the thickness, length and area of the regenerated epidermis postwounding. Immunohistochemical staining for markers of EpSCs (α6 integrin and ß1 integrin) and cell proliferation (PCNA) shows that the number and proliferation of EpSCs in the basal layer of the epidermis are reduced in ANGPTL4-deficient mice. In vitro studies show that ANGPTL4 deficiency impedes EpSC proliferation, causes cell cycle arrest at the G1 phase and reduces the expressions of cyclins D1 and A2, which can be reversed by ANGPTL4 overexpression. ANGPTL4 deletion suppresses EpSC migration, which is also rescued by ANGPTL4 overexpression. Overexpression of ANGPTL4 in EpSCs accelerates cell proliferation and migration. Collectively, our results indicate that ANGPTL4 promotes EpSC proliferation by upregulating cyclins D1 and A2 expressions and accelerating the cell cycle transition from G1 to S phase and that ANGPTL4 promotes skin wound re-epithelialization by stimulating EpSC proliferation and migration. Our study reveals a novel mechanism underlying EpSC activation and re-epithelialization during cutaneous wound healing.

Is the oblique branch of the lateral circumflex femoral artery a common variant?

The oblique branch of the lateral circumflex femoral artery, a short branch of the deep femoral artery, is highly prevalent (32-46%) and is usually considered a normal variant, although this is still controversial. This study aimed to evaluate whether the oblique branch of the lateral circumflex femoral artery is a variant. We reviewed medical record data of patients with skin and soft tissue defects of the extremities who underwent flap repair using free anterolateral thigh (ALT) flaps at our hospital in 2019. The anatomical characteristics of the flaps were examined intraoperatively by high-frequency color Doppler ultrasound. A total of 153 ALT flaps from 146 patients were included. Among the branches, 232 (73.7%) were oblique branches, and 83 (26.4%) were descending branches. Of the 232 oblique branches, 141 (60.8%) were from septocutaneous branches, and the other 83 (39.2%) were from musculocutaneous branches. In addition, 20 (24.1%) descending branches were from septocutaneous branches, and the other 63 (75.9%) were from musculocutaneous branches. Analyzing the prevalence of the oblique branch in septocutaneous branches, more than half of the patients had oblique branches rather than descending branches. The high proportion of oblique branches from septocutaneous branches (median: 100 (0-100) vs. 0 (0-50), p = 0.002) supports the understanding that the oblique branch is a normal anatomical element rather than a variant. The main type was the intramuscular branches, which required significantly less time for flap harvesting. The oblique branch may be the preferred vascular pedicle for free ALT flaps.

The modified second toe flap technique based on the dorsal digital artery of the toe in finger pulp reconstruction.

BACKGROUND: The second toe flap is a widely used innervated neurovascular flap for repairing finger pulp defects. It mainly carries the proper plantar digital artery and nerve. But the donor site morbidity and arterial injury are common. The report retrospectively evaluated the clinical outcomes of the second toe free medial flap based on dorsal digital artery of the toe to investigate the esthetics and function in the treatment of soft tissue defects of fingertip pulp. METHODS: From March 2019 to December 2020, 12 patients with finger pulp defects (seven acute crush, three cut, and two burn) undergoing the modified second toe flap were chosen for retrospective review. The average patient age was 38.6 (range: 23-52) years. The mean defect size was 2.1 × 1.6 (range: 1.5 × 1.3-2.6 × 1.9) cm. The defects did not extend beyond the distal interphalangeal joint and the phalanges were not damaged in all cases. The average follow-up was 9.5 (range: 6-16) months. Demographic information, flap data, and perioperative characteristics were collected. RESULTS: The mean size of the modified flap was 2.3 × 1.8 (range: 1.7 × 1.5-2.7 × 2.0) cm and mean diameter of artery was 0.61 (range: 0.45-0.85) mm. The mean flap harvested time and operation time were 22.6 (range: 16-27) minutes and 133.7 (range: 101-164) minutes. A flap was ischemic after first day postoperatively and later it improved by releasing the sutures. All flaps were survival without necrosis. One patient was not satisfied with the appearance of the finger pulp because of scar hyperplasia. The other 11 patients were satisfied with the appearance and function of the injured digit after 6 months postoperatively. CONCLUSION: The modified second toe flap technique based on the dorsal digital artery of the toe is a feasible choice to reconstruct the sensation and appearance of the injured fingertip with current microsurgical techniques.

Combined light-cured and sacrificial hydrogels for fabrication of small-diameter bionic vessels by 3D bioprinting.

BACKGROUND: Bionic grafts can replace autologous tissue through tissue engineering in cases of cardiovascular disease. However, small-diameter vessel grafts remain challenging to precellularize. OBJECTIVE: Bionic small-diameter vessels with endothelial and smooth muscle cells (SMCs) manufactured with a novel approach. METHODS: A 1-mm-diameter bionic blood vessel was constructed by combining light-cured hydrogel gelatin-methacryloyl (GelMA) with sacrificial hydrogel Pluronic F127. Mechanical properties of GelMA (Young's modulus and tensile stress) were tested. Cell viability and proliferation were detected using Live/dead staining and CCK-8 assays, respectively. The histology and function of the vessels were observed using hematoxylin and eosin and immunofluorescence staining. RESULTS: GelMA and Pluronic were printed together using extrusion. The temporary Pluronic support was removed by cooling during GelMA crosslinking, yielding a hollow tubular construct. A bionic bilayer vascular structure was fabricated by loading SMCs into the GelMA bioink, followed by perfusion with endothelial cells. In the structure, both cell types maintained good cell viability. The vessel showed good histological morphology and function. CONCLUSION: Using light-cured and sacrificial hydrogels, we formed a small ca bionic vessel with a small caliber containing SMCs and endothelial cells, demonstrating an innovative approach for construction of bionic vascular tissues.

Morphological study of branches of lateral femoral circumflex artery based on digital subtraction angiography.

In this study, the digital subtraction angiography (DSA) data were used to describe the number, course, and distribution of the branches of the lateral circumflex femoral artery (LCFA), in order to provide an imaging basis for the application of the anterolateral thigh flap pedicled with each branch of the LCFA. The number, location, direction, and distribution of the branches of the LCFA were analyzed by selective DSA angiography in 113 patients who needed an anterolateral thigh flap to repair the wound. LCFA usually originates from the deep femoral artery or femoral artery and routinely sends out four main branches: ascending branch, transverse branch, oblique branch, and descending branch. The ascending branch is about 45 °outward and upward with the horizontal axis of the body; the transverse branch is roughly parallel to the horizontal axis of the body to the outside of the thigh or slightly upward or downward; the oblique branch is about 45 °outward and downward to the body's long axis or horizontal axis and gradually turns parallel to the body's long axis; the 5∼10 cm at the beginning of the descending branch is parallel to the long axis of the body, and the internal and external branches are separated near the midpoint of the line between the anterior superior iliac spine and the lateral edge of the patella. It is of high reference value to use DSA technology to analyze the morphological characteristics of LCFA.

Transplantation of Ultra-Long Cross-Donor Conjoined Perforator Flaps with Multiple Blood Supply Sources for Wound Repair.

OBJECTIVE: There are reports about the surgical method and clinical efficacy of using ultra-long cross-donor perforator skin flap transplantation with multiple blood supply sources to repair wounds. METHOD: Between January 2013 and March 2019, 29 wounds were repaired using ultra-long skin flaps from the donor site of the chest, abdomen and anterolateral thigh. All patients were followed up on a regular basis with a view to the following: appearance of skin flap, function of recipient area and healing of donor area. RESULT: After the operation, all 28 skin flaps were fine. On the fifth day after the operation, one case of a 47-cm anterolateral thigh flap had dark skin color in the distal-most area measuring about 5 cm×4 cm, and the incision showed slow bleeding. In 11 cases, linear scars with soft edges and no obvious contractures were left in the donor area of the chest and abdomen. Eighteen cases with lateral femoral donor sites healed successfully, with linear scars forming without contracture. Three cases with lateral femoral donor sites had wide linear scars that were slightly above skin level and exhibited no contracture. CONCLUSION: Transplantation of ultra-long conjoined cross-donor perforator flaps with multiple blood supply is beneficial to wound repair and worthy of clinical promotion.

Bioprinting a skin patch with dual-crosslinked gelatin (GelMA) and silk fibroin (SilMA): An approach to accelerating cutaneous wound healing.

Clinical settings often face significant obstacles in treating large acute wounds. The alternative of therapeutic approach is needed urgently. Hydrogels derived from natural or synthetic materials may be designed to perform a variety of functions for promoting wound healing. Herein, a 3D bioprinted hydrogel patch is designed for accelerating acute wound healing, which is fabricated with methacryloyl-substituted gelatin (GelMA) and silk fibroin (SilMA) dual-cross-linked by ultraviolet (UV) light. The GelMA with added silk fibroin (GelSilMA) shows improved biodegradation and mechanical properties. Furthermore, SilMA hydrogel can maintain a moisturized healing environment in wound area persistently with adequate degradation capacity. In vivo, GelSilMA (G-S) hydrogel can help to speed wound closure by the improved microenvironment for epidermal tissue regeneration and endogenous collagen generation accordingly. In summary, the G-S hydrogel patch can accelerate acute wound healing efficiently in a relatively simple and inexpensive manner.

Repair of Compound Dorsal Defects of the Digits Using a Free Antegrade Palmaris Longus Tendocutaneous Venous Flap.

PURPOSE: To investigate the clinical effect of repairing small dorsal digit compound tissue defects using a free palmaris longus tendocutaneous flap nourished by venous blood. METHODS: In a retrospective analysis of patients treated between March 2010 and October 2017, 18 patients were identified as having small compound tissue defects, which were repaired using a free palmaris longus tendocutaneous flap nourished by venous blood. The average age of the patients, including 15 male and 3 female patients, was 34 years (range, 22-55 years). The mean wound size was 6 cm2 (range, 2.0 × 1.5 to 3.5 × 2.0 cm2). All the patients had dorsal defects. The average length of extensor tendon defect was 2.0 cm (range, 1.0-3.0 cm). The mean area of the flap was 7 cm2 (range, 2.5 × 2.0 to 4.0 × 3.5 cm2). The donor sites were primarily closed. RESULTS: All 18 flaps survived. A vascular crisis due to a venospasm occurred within 48 hours in 3 flaps, but ultimately, all the flaps survived. The patients were followed-up for a mean period of 10 months (range, 3-15 months). All the patients returned to their previous work after 10-12 weeks. No pain or scar contracture was reported in either the recipient or donor site. CONCLUSIONS: The free antegrade palmaris longus tendocutaneous venous flap enabled the repair of compound tissue defects of the dorsal digit, resulting in acceptable aesthetics, repaired tendon defects, and wound coverage. This surgical method is an option for the reconstruction of small compound defects of digits with extensor defects. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Reconstruction of the central slip insertion of the extensor tendon with the partial slip of the flexor digitorum superficialis tendon.

INTRODUCTION: To introduce the surgical approach and clinical effect of transferring the partial slips of the flexor digitorum superficialis (FDS) tendon to reconstruct the insertion of the central slip of the extensor tendon (CSET) through an established bone tunnel (BT). MATERIALS AND METHODS: From April 2019 to March 2021, nine patients (six males and three females) with the CSET insertion rupture or defect were admitted to the institution and the CSET insertion was reconstructed with partial tendon slips on both sides of the FDS. The active range of motion of the interphalangeal joint of the affected finger was measured by a goniometer, the degree of pain was evaluated by visual analogue scale (VAS), and the grip strength of the affected limb was measured by an electronic hand dynamometer. RESULTS: The average postoperative follow-up was 12 months. No complications occurred. At the last follow-up, six of the patients were very satisfied and three were satisfied with their recovery. CONCLUSION: The reconstruction of the CSET insertion by transferring the partial tendon slips of the FDS seem to be safe and feasible with minimal invasion to the donor tendon. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

[Clinical application of anterolateral thigh perforator flap pedicled with oblique branch in intramuscular of lateral circumflex femoral artery].

Objective: To explore the characteristics and clinical application of the anterolateral thigh flap pedicled with the oblique branch in the intramuscular of lateral circumflex femoral artery. Methods: The clinical data of 25 patients with skin and soft tissue defects of extremities admitted between December 2020 and April 2021 were retrospectively analyzed, including 16 males and 9 females, aged 14-75 years, with the median age of 43 years. The defect site included 13 cases of hand, 2 cases of forearm, 2 cases of calf, and 8 cases of foot and ankle. The wound area ranged from 6 cm×4 cm to 35 cm×22 cm. Twenty-four patients with trauma were admitted to hospital immediately after injury, and 1 patient with diabetic foot infection was transferred to the hospital after ineffective treatment in other hospital. Flap surgery was performed from 0 to 56 days (median, 22 days) after admission. A total of 26 thigh flaps were harvested in 25 patients, with unilateral flaps in size of 7 cm×5 cm to 40 cm×10 cm. The type, caliber, and location of the perforating branch were recorded during the operation, and the anatomical characteristics of the oblique branch of the intramuscular trunk were mainly observed. The flap harvesting time was recorded; the flap survival and wound healing time were observed; at last follow-up, XIAO Feipeng et al. flap comprehensive efficacy evaluation table was used to evaluate the effectiveness of flap repair from three aspects of donor site, recipient site, and subjective satisfaction of doctors and patients. Results: After the oblique branch in intramuscular of lateral circumflex femoral artery was sent out, it ran 2-3 cm obliquely laterally and inferiorly in the intermuscular septum and then entered the vastus lateralis muscle, and sent out perforating branches to nourish the skin. A total of 61 perforating branches were marked in 26 thighs of 25 patients before operation, and 70 perforating branches were found during operation, including 9 transverse branches, 29 descending branches, and 32 oblique branches, all of the oblique branches were musculocutaneous perforators. All 25 patients were followed up 6-10 months, with an average of 8 months. The time of unilateral thigh flap harvesting ranged from 13 to 90 minutes, with an average of 48 minutes. One patient with diabetes developed disturbance of blood supply and complete necrosis of the flap at 1 month after operation, and then the flap was repaired with skin graft; 1 case developed arterial crisis after operation, which survived after timely exploration; and the rest of the flaps survived smoothly. The wound healing time of the recipient site ranged from 10 to 44 days, with an average of 19 days, and the donor site of the thigh healed by first intention. At last follow-up, the color and texture of the flap was good and the sensation recovered to S 1-S 2. Only linear scar was left in the donor site, no scar contracture, pain, and other discomfort occurred, and no other serious complications occurred. Evaluated by flap comprehensive efficacy evaluation table, the score was 74-93, with an average of 88, of which 10 cases were excellent, 13 cases were good, and 2 cases were fair, with an excellent and good rate of 92%. Conclusion: The intramuscular trunk oblique branch is not uncommon, and its trunk course and perforators distribution are regular. To improve the understanding of this type of oblique branch and adopt appropriate methods during operation can improve the success rate of skin flap extraction.

miR-100-5p Promotes Epidermal Stem Cell Proliferation through Targeting MTMR3 to Activate PIP3/AKT and ERK Signaling Pathways.

Skin epidermal stem cells (EpSCs) play a critical role in wound healing and are ideal seed cells for skin tissue engineering. Exosomes from human adipose-derived stem cells (ADSC-Exos) promote human EpSC proliferation, but the underlying mechanism remains unclear. Here, we investigated the effect of miR-100-5p, one of the most abundant miRNAs in ADSC-Exos, on the proliferation of human EpSCs and explored the mechanisms involved. MTT and BrdU incorporation assays showed that miR-100-5p mimic transfection promoted EpSC proliferation in a time-dependent manner. Cell cycle analysis showed that miR-100-5p mimic transfection significantly decreased the percentage of cells in the G1 phase and increased the percentage of cells in the G2/M phase. Myotubularin-related protein 3 (MTMR3), a lipid phosphatase, was identified as a direct target of miR-100-5p. Knockdown of MTMR3 in EpSCs by RNA interference significantly enhanced cell proliferation, decreased the percentage of cells in the G1 phase and increased the percentage of cells in the S phase. Overexpression of MTMR3 reversed the proproliferative effect of miR-100-5p on EpSCs, indicating that miR-100-5p promoted EpSC proliferation by downregulating MTMR3. Mechanistic studies showed that transfection of EpSCs with miR-100-5p mimics elevated the intracellular PIP3 level, induced AKT and ERK phosphorylation, and upregulated cyclin D1, E1, and A2 expression, which could be attenuated by MTMR3 overexpression. Consistently, intradermal injection of ADSC-Exos or miR-100-5p-enriched ADSC-Exos into cultured human skin tissues significantly reduced MTMR3 expression and increased the thickness of the epidermis and the number of EpSCs in the basal layer of the epidermis. The aforementioned effect of miR-100-5p-enriched ADSC-Exos was stronger than that of ADSC-Exos and was reversed by MTMR3 overexpression. Collectively, our findings indicate that miR-100-5p promotes EpSC proliferation through MTMR3-mediated elevation of PIP3 and activation of AKT and ERK. miR-100-5p-enriched ADSC-Exos can be used to treat skin wound and expand EpSCs for generating epidermal autografts and engineered skin equivalents.

A Method to Visualize and Quantify the Intraosseous Arteries of the Femoral Head by Vascular Corrosion Casting.

OBJECTIVE: To describe a method to display the three-dimensional distribution of intraosseous arteries in the femoral head by vascular corrosion casting. METHODS: An experimental study was done to expose the intraosseous arteries of the femoral head by a microperfusion corrosion method between January 2021 and May 2021. Specimens were 23 swine femoral heads (12 female specimens and 11 male specimens, where age of swine ranged from 8 to 12 months, and the weight was approximately 150 kg). The femoral heads were microperfused with the vascular casting resin through retinacular arteries, and the bone of the femoral head was dissolved with 50% sodium hydroxide and 10% hydrochloric acid and rinsed under the microscope until the vessel casts were completely exposed. The distribution and anastomosis of the arteries in the femoral head were observed under direct vision and microscopy. The diameter of the artery in the femoral head was measured at 0.5 cm after its entry into the bone of the femoral head with a microscale under the microscope. The number of internal arteries with diameter ≥0.05 mm was counted. The number and diameter of the main trunk of the epiphyseal arteries in the femoral head between male and female swine were compared. RESULTS: The vascular casting specimen of the swine femoral head was successfully produced by using epoxy resin as a casting agent, and the three-dimensional intraosseous vascular structures were clearly visible. The number of epiphyseal arteries in male and female swine was 8.55 ± 2.15 and 8.83 ± 2.15 (t = -0.31, p = 0.38), respectively. The diameters of the superior epiphyseal arteries in male and female swine were 0.35 ± 0.09 and 0.31 ± 0.08 mm (t = 1.03, p = 0.16), the diameters of the inferior epiphyseal arteries were 0.47 ± 0.05 and 0.49 ± 0.09 mm (t = -0.57, p = 0.29), and the diameters of the anterior epiphyseal arteries were 0.34 ± 0.08 and 0.33 ± 0.13 mm (t = 0.32, p = 0.37). There was no significant difference in the number and diameter of the main trunk of intraosseous arteries between male and female swine (p > 0.05). The main trunk of intraosseous arteries formed an anastomosis in the center of the femoral head. Among 23 swine femoral head samples, three types of intraosseous anastomosis were observed, including 13 (57%) posterior superior-posterior inferior, seven (30%) posterior inferior-anterior, and three (13%) uniform intraosseous anastomosis. CONCLUSION: The microperfusion corrosion method can produce the vascular casting specimen of swine femoral head revealing the three-dimensional structure of the intraosseous artery, which clearly shows the origin, course and branches, and diameter, as well as the anastomosis, of nutrient arteries in the femoral head. This method provides a simple and rapid technique for quantifying and visualizing intraosseous arteries.

Bioprinting small-diameter vascular vessel with endothelium and smooth muscle by the approach of two-step crosslinking process.

Three-dimensional bioprinting shows great potential for autologous vascular grafts due to its simplicity, accuracy, and flexibility. The 6-mm-diameter vascular grafts are used in clinic. However, producing small-diameter vascular grafts are still an enormous challenge. Normally, sacrificial hydrogels are used as temporary lumen support to mold tubular structure which will affect the stability of the fabricated structure. In this study, we have developed a new bioprinting approach to fabricating small-diameter vessel using two-step crosslinking process. The » lumen wall of bioprinted gelatin mechacrylate (GelMA) flat structure was exposed to ultraviolet (UV) light briefly for gaining certain strength, while ¾ lumen wall showed as concave structure which remained uncrosslinked. Precrosslinked flat structure was merged towards the uncrosslinked concave structure. Two individual structures were combined tightly into an intact tubular structure after receiving more UV exposure time. Complicated tubular structures were constructed by these method. Notably, the GelMA-based bioink loaded with smooth muscle cells are bioprinted to form the outer layer of the tubular structure and human umbilical vein endothelial cells were seeded onto the inner surface of the tubular structure. A bionic vascular vessel with dual layers was fabricated successfully, and kept good viability and functionality. This study may provide a novel idea for fabricating biomimetic vascular network or other more complicated organs.

Risk and prognostic factors of replantation failure in patients with severe traumatic major limb mutilation.

PURPOSE: Traumatic mutilation of major limbs can result in limb loss, motor disability, or death. Patients who had replantation failure needed to undergo additional surgeries (even amputation) and had a longer length of hospital stay. Here, we determined the risk and prognostic factors of replantation failure in patients with traumatic major limb mutilation. METHODS: This retrospective study included adult inpatients with severed traumatic major limb mutilation who underwent replantation from Suzhou Ruixing Medical Group from October 18, 2016 to July 31, 2020. Demographic, and clinical characteristics including traumatic conditions, laboratory findings, mangled extremity severity scores (MESS), treatments, and outcomes of the patients were collected. Data were used to analyze predictors and risk factors for replantation failure. RESULTS: Among the 66 patients, 48 (72.7%) were males, the median age was 47.0 years old. Replantation failure occurred in 48 patients (72.7%). The area under the curve of the joint prediction of lactic acid on admission, 72-h cumulative fluid balance, and albumin level immediately postoperatively was 0.838 (95% confidence interval [CI], 0.722-0.954; P < 0.001) with a sensitivity of 89.7% and a specificity of 69.2%. Lower limb trauma (odds ratio [OR] 8.65, 95% CI 1.64-45.56, P = 0.011), mangled extremity severity scores (OR 2.24, 95% CI 1.25-4.01, P = 0.007), and first 72-h cumulative fluid balance > 4885.6 mL (OR 10.25, 95% CI 1.37-76.93, P = 0.024) were independent risk factors for replantation failure. CONCLUSIONS: Lower limb trauma, mangled extremity severity scores, and cumulative water balance were associated with replantation failure, implying that fluid management is necessary for major limb salvage. More studies are needed to explore the predictive power of indicators related to tissue oxygenation and wound healing for replantation failure.

Sinus Tarsi Approach With Percutaneous Screw Fixation for Intra-Articular Calcaneal Fractures.

The aim of this study was to evaluate the outcomes of surgical treatment of intra-articular calcaneal fractures by using the sinus tarsi approach combined with percutaneous medial reduction by leverage technique and percutaneous screw fixation. We assessed the outcomes of 29 patients treated using sinus tarsi approach with percutaneous screw fixation. All patients were evaluated both clinically and radiologically. The Böhler and Gissane angle were evaluated postoperatively using radiographs. During the median follow-up period of 27.0 ± 10.3 months, no cases with failure to reduce or displace hardware were detected. All cases achieved the restoration of a normal Böhler and Gissane angle. The median preoperative Böhler angle was 12.3° ± 2.5° while postoperatively it was 30.5° ± 5.7° (p < .01). The median preoperative Gissane angle was 98.1° ± 7.5°, which was 125.9° ± 3.6° postoperatively (p < .01). At the last follow-up, the median American Orthopedic Foot and Ankle Society hindfoot score was 87.7 ± 5.9, and the median Maryland foot score was 88.6 ± 5.9. Our technique for intra-articular calcaneal fractures can effectively correct calcaneal tuberosity outward displacement, medial wall overlapping, and the hindfoot varus deformity with less soft tissue damage. This technique is a good alternative for the treatment of calcaneal fractures, resulting in minimal soft tissue damage, few wound complications, and excellent radiological and clinical outcomes.