[Effects of tensile force on the vascular lumen formation in three-dimensional printed tissue]

Objective: To explore the effects of tensile force on vascular lumen formation in three-dimensional printed tissue. Methods: The experimental research method was used. Human umbilical vein endothelial cells (HUVECs) were extracted from discarded umbilical cord tissue of 3 healthy women (aged 22 to 35 years) who gave birth in the Department of Gynaecology and Obstetrics of Suzhou Ruihua Orthopaedic Hospital from September 2020 to May 2021. Human skin fibroblasts (HSFs) were extracted from discarded normal skin tissue of 10 male patients (aged 20 to 45 years) who underwent wound repair in the Department of Hand Surgery of Suzhou Ruihua Orthopaedic Hospital from September 2020 to September 2022. After identification of the two kinds of cells, the 4th to 6th passage of cells were taken for the follow-up experiments. HUVECs and HSFs were used as seed cells, and polycaprolactone, gelatin, hyaluronic acid, and fibrin were used as scaffold materials, and the three-dimensional printed vascularized tissue was created by three-dimensional bioprinting technology. The printed tissue with polycaprolactone scaffold of 6 and 10 mm spacing, and without polycaprolactone scaffold were set as 6 mm spacing polycaprolactone group, 10 mm spacing polycaprolactone group, and non-polycaprolactone group, respectively. After 4 days of culture, the printed tissue in 10 mm spacing polycaprolactone group was selected to detect the cell survival by cell viability detection kit, and the cell survival rate was calculated. After 14 days of culture, the printed tissue in three groups were taken, and the shape change of tissue was observed by naked eyes; immunofluorescence staining was performed to observe the arrangement of filamentous actin, and lumen diameter, total length, and number of branches of vessel in the tissue. The tissue with micro-spring structure in the above-mentioned three groups was designed, printed, and cultured for 9 days, and the tensile force applied in the printed tissue was measured according to the force-displacement curve. The number of samples was all 3 in the above experiments. Data were statistically analyzed with one-way analysis of variance and Tukey test. Results: After 4 days of culture, the cell survival rate in printed tissue in 10 mm spacing polycaprolactone group was (91.3±2.2)%. After 14 days of culture, the shape change of printed tissue in non-polycaprolactone group was not obvious, while the shape changes of printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group were obvious. After 14 days of culture, the arrangement of filamentous actin in the printed tissue in non-polycaprolactone group had no specific direction, while the arrangement of filamentous actin in the printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group had a specific direction. After 14 days of culture, The vascular lumen diameters of the printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group were (6.0±1.3) and (10.8±1.3) μm, respectively, which were significantly larger than 0 μm in non-polycaprolactone group (P<0.05), and the vascular lumen diameter of printed tissue in 10 mm spacing polycaprolactone group was significantly larger than that in 6 mm spacing polycaprolactone group (P<0.05); the total length and number of branches of blood vessel in the printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group were significantly shorter or less than those in non-polycaprolactone group (P<0.05), and the total length and number of branches of blood vessel in the printed tissue in 10 mm spacing polycaprolactone group were significantly shorter or less than those in 6 mm spacing polycaprolactone group. After 9 days of culture, the tensile forces applied in the printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group were (2 340±59) and (4 284±538) μN, respectively, which were significantly higher than 0 μN in non-polycaprolactone group (P<0.05), and the tensile force applied in the printed tissue in 10 mm spacing polycaprolactone group was significantly higher than that in 6 mm spacing polycaprolactone group (P<0.05). Conclusions: The three-dimensional printed scaffold structure can exert different tensile force in the printed tissue, and the vascular lumen diameter of the printed tissue can be regulated by adjusting the tensile force.

[Comparative study of the effects between second toe tibial dorsal artery flap and second toe tibial plantar proper artery flap in repairing finger skin and soft tissue defects]

Objective: To compare the effects between second toe tibial dorsal artery flap (2-TDAF) and second toe tibial plantar proper artery flap (2-TPPAF) in repairing finger skin and soft tissue defects. Methods: A retrospective cohort study was conducted. From January 2019 to June 2020, 27 patients with skin and soft tissue defects at the fingertips with area of 1.5 cm×1.2 cm-2.6 cm×1.8 cm after debridement who met the inclusion criteria were admitted to Suzhou Ruihua Orthopaedic Hospital, including 21 males and 6 females, aged 19-59 (37±10) years. According to flap repair methods used in the defective fingers, the patients were divided into 2-TDAF group (12 cases) and 2-TPPAF group (15 cases). The area of 2-TDAF ranged from 1.5 cm×1.2 cm to 2.5 cm×1.6 cm, and the area of 2-TPPAF ranged from 1.7 cm×1.3 cm to 2.6 cm×1.8 cm. Full-thickness skin grafts from the medial side of the ipsilateral leg were grafted to the wounds in donor sites, and the wounds in donor sites of skin grafts were directly sutured. Flap arterial diameter, flap excision time, flap survival situation of patients in 2 weeks after operation, and follow-up time were recorded. At the last follow-up, the two-point discrimination distance of flap graft site, total action motion (TAM) of the finger joints, and wound healing of the flap donor site were recorded; the Vancouver scar scale (VSS) was used to score the scar in donor area of the second toe and the recipient area of fingers; the appearance and self-satisfaction subscales of the Michigan hand outcomes questionnaire (MHQ) were used to evaluate the affected finger. Data were statistically analyzed with independent sample t test or Fisher's exact probability test. Results: The flap artery diameter of patients in 2-TDAF group was 0.35-0.80 (0.56±0.14) mm and the flap cutting time was (14.0±2.7) min, which were significantly shorter than 0.80-1.35 (1.02±0.16) mm and (19.7±3.4) min in 2-TPPAF group (with t values of 7.81 and 4.79, respectively, P<0.01). The flaps of patients in the 2 groups in recipient areas survived well in 2 weeks after operation, and the wounds in donor areas of flaps of patients in the 2 groups healed well at the last follow-up. There was no statistically significant difference in the postoperative follow-up time, and two-point discrimination distance of flap graft site, TAM of the finger joints, VSS score of scar in the second toe donor site and the finger recipient site, and the appearance and self-satisfaction of MHQ scores of the affected finger at the last follow-up (P>0.05). Conclusions: Compared with 2-TPPAF, 2-TDAF has a shallower anatomical layer and shorter time for surgical flap removal, which can preserve the proper arteries and nerves at the base of the toes and reduce the damage to the donor site.

[Clinical effects of proximal ulnar artery perforator flap combined with iliac bone graft in the reconstruction of subtotal thumb or finger defects]

Objective: To explore the clinical effects of proximal ulnar artery perforator flap combined with iliac bone graft in the reconstruction of subtotal thumb or finger defects. Methods: A retrospective observational study was conducted. From August 2016 to August 2019, 7 patients with thumb or finger defects caused by mechanical damage who met the inclusion criteria were admitted to Ruihua Affiliated Hospital of Soochow University, including 6 males and 1 female, aged 46 to 58 years. Their length of fingers was repaired with iliac bone, with length of 2.0 to 3.0 cm. After the bone graft, the skin defect area of the affected finger ranged from 2.8 cm×2.2 cm to 6.0 cm×3.2 cm. Then the free proximal ulnar artery perforator flap with area of 3.0 cm×2.4 cm to 6.5 cm×3.5 cm was used to cover the wounds. The wounds in donor sites of iliac crest and flap were directly sutured. The survival of flap in one week post surgery and the donor site wound healing in 2 weeks post surgery were observed, respectively. During the follow-up, the appearance and sensory function of the affected finger, bone healing, and scar hypertrophy of wound in the donor site were observed and evaluated. At the last follow-up, the functional recovery of the affected finger was evaluated with trial standard for the evaluation of functions of the upper limbs of the Hand Surgery Society of Chinese Medical Association. Results: In one week post surgery, all the flaps survived. In 2 weeks post surgery, the iliac bone and the wounds in forearm donor site healed. During the follow-up of 5 to 13 months, the flap was good in appearance, without obvious pigmentation; the sensory recovery reached level S2 in 5 patients and S0 in 2 patients; all the grafted iliac bones were bony union without obvious resorption; the wounds in donor site healed well, with only mild scar formation. At the last follow-up, the shape of the reconstructed finger was close to the healthy finger, and the functional evaluation results were excellent in 3 cases and good in 4 cases. Conclusions: The use of proximal ulnar artery perforator flap combined with iliac bone graft to reconstruct subtotal thumb or finger can partially restore part of the appearance and function, with less damage to the donor site. It is a good choice for patients who have low expectations of appearance and function for the reconstructed finger.

[Clinical effects of extra-long lateral femoral supercharged perforator flaps in repair of foot and ankle wounds]

Objective: To investigate the clinical effects of extra-long lateral femoral supercharged perforator flaps in repair of ankle and foot wounds. Methods: From March 2014 to October 2018, 16 patients with foot and ankle injuries were admitted to our hospital and left large area of wounds on foot and ankle after emergency treatment. There were 13 males and 3 females, with age of 27 to 60 years. The area of the wounds ranged from 14 cm×10 cm to 40 cm×17 cm. The wounds were repaired with extra-long lateral femoral supercharged perforator flaps. The widths of flaps in 8 patients were longer than 8 cm, and the bilobed flaps were designed to repair the wounds. The area of the flaps ranged from 12 cm×5 cm to 40 cm×9 cm. During the operation, 54 perforators were detected, with an average of 3.2 perforators in each flap, and 36 source arteries of perforators were detected. The blood vessel trunk of 15 patients was descending branch of the lateral femoral circumflex artery, and their supercharged mode was anastomosis of the bulky perforator of descending branch of the lateral femoral circumflex artery with the oblique branch of the lateral femoral circumflex artery and/or medial femoral circumflex artery or the descending branch of superficial illiac circumflex artery. The blood vessel trunk of 1 patient was oblique branch of the lateral femoral circumflex artery, and the supercharged mode of the patient was anastomosis of the oblique branch of the lateral femoral circumflex artery with the bulky perforator of the descending branch of the lateral femoral circumflex artery. The wounds were covered with the flaps after supercharged blood vessel anastomosis, and blood vessels in the donor sites were anastomosed with those in the recipient sites. The donor site was sutured directly. The survival of the flap after the operation and healing time of the wound, and the flap condition, the two-point discrimination distance of flap in patients who were reconstructed with sensation, the recovery of the ankle function, and the appearance of the donor site during follow-up were recorded. Results: A total of 17 flaps in 16 patients were designed, including 8 bilobed flaps and 9 non-lobulated flaps. Sixteen flaps in 15 patients survived. Vascular crisis occurred in the flap of one patient, and the flap survived when the vascular crisis was relieved by the second operation. The healing time of foot and ankle wounds ranged from 12 to 90 days. All the lateral femoral donor sites healed completely. During follow-up of 8 to 48 months, flaps in 2 patients were slightly bloated and were trimmed in 6 months after the operation. The other flaps were with good appearance, soft texture, good elasticity, and no rupture or ulceration. The two-point discrimination distances of flaps ranged from 7 to 16 mm in 8 patients who were reconstructed with sensation, and the other flaps recovered protective sensation. The flexion and extension function of ankle joint recovered well, and the walking function was not affected significantly. All donor sites formed linear scar, with no deep tissue infection such as osteomyelitis. Conclusions: The application of extra-long lateral femoral supercharged perforator flaps to repair the large area of wounds in foot and ankle can significantly reduce damage to donor sites and has advantages of rich blood supply and good safety, thus it has satisfactory clinical effects.

Increased miR-155-5p expression in dermal mesenchymal stem cells of psoriatic patients: comparing the microRNA expression profile by microarray

Mesenchymal stem cells (MSCs) have pleiotropic immuno-modulatory effects and pro-angiogenic ability, leading to the presumption that MSCs may be involved in the pathogenesis of many inflammatory or autoimmune disorders, including psoriasis. In a previous study, we reported the specific gene expression profile of dermal MSCs from psoriasis. Inflammation- and angiogenesis-related genes, such as lipopolysaccharide-induced tumor necrosis factor-alpha transcription factor (LITAF), dual-specificity protein phosphatase 1 (DUSP1), vascular endothelial growth factor α (VEGFα), and insulin-like growth factor-binding protein-5 (IGFBP5), are abnormally expressed in psoriatic dermal MSCs. As a key regulator of gene expression, miRNA are involved in a wide variety of biological processes; in fact, several miRNAs have been implicated in the development and progression of inflammatory or autoimmune disorders. In this study, we compared the miRNA expression profiles of dermal MSCs from patients with psoriasis to those in MSCs from normal individuals by microarray, and found that the pro-inflammatory miRNA miR-155 was significantly overexpressed in psoriatic MSCs (2.44 fold, P < 0.001). Additionally, the expression of miR-155 target gene TAB2 (8.47 ± 1.55 vs 6.38 ± 2.10, P < 0.01,) and the downstream gene iNOS (5.26 ± 2.58 vs 3.73 ± 1.89, P < 0.05) was found to be inhibited in psoriatic dermal MSCs by real-time PCR. Therefore, we speculated that the elevation in miR-155 levels may be an indicator of, or a key regulatory pathway in, the pathogenesis of psoriasis, resulting in functionally impaired dermal MSCs.

LITAF, HHEX, and DUSP1 expression in mesenchymal stem cells from patients with psoriasis

Psoriasis is a common chronic relapsing inflammatory skin disease, in which mesenchymal stem cells (MSCs) have been hypothesized to play an important role in abnormal localized inflammation and vascular proliferation observed in skin lesions. Previous studies have revealed abnormal gene expression patterns, DNA methylation status, and cytokine secretion of MSCs in psoriatic skin lesions, as well as some gene expression abnormalities related to inflammation and angiogenesis. We further verified the gene and protein expressions of inflammation-related lipopolysaccharide-induced tumor necrosis factor-alpha transcription factor (LITAF), dual-specificity protein phosphatase 1 (DUSP1), and angiogenesis-related hematopoietically expressed homeobox (HHEX) in MSCs derived from the skin lesions of psoriasis patients. The gene expression of LITAF, DUSP1, and HHEX in dermal MSCs was measured at the mRNA level using reverse transcription-polymerase chain reaction and the corresponding protein expression levels were analyzed by western blotting analysis. The gene and protein expression levels of LITAF, HHEX, and DUSP1 in dermal MSCs were significantly lower in psoriasis patients compared to controls. Amplification and western blotting results were consistent with our previously reported gene chip data. Our results suggest that dermal MSCs in psoriatic skin lesions may be involved in the development, progression, and regulation of localized inflammatory abnormalities by reducing the expression of LITAF, HHEX, and DUSP1, which are related to inflammation and angiogenesis.

Impact of BMMSCs from different sources on proliferation of CD34⁺ cells

There are significant differences on the biological characteristics of bone marrow mesenchymal stem cells (BMMSCs), immunological response, and antigen-presenting functions between patients with psoriasis and normal subjects, but there are no significant differences in aborted fetuses. We examined the differences in BMMSCs between aborted fetuses and patients with psoriasis in this study. Bone marrow from normal subjects, aborted fetuses, and patients with psoriasis were obtained using a MidiMACS machine. Density gradient centrifugation method was used to isolate the bone marrow mononuclear cells of patients with psoriasis and aborted fetus and the cells were cultivated. Bone marrow CD34(+) cells from normal subjects were isolated. MTT colorimetric detection was used to test the proliferation activity of bone marrow CD34(+) cells. The purity of bone marrow CD34(+) cells and BMMSCs was determined by flow cytometry. The BMMSC culture supernatant fluid of patients with psoriasis and aborted fetuses showed no statistically significant difference with bone marrow CD34(+) cell proliferation in normal subjects (P > 0.05).

[Treatment of gut-derived endotoxemia with lactulose. An experimental study]

Endotoxemia plays an important role in the origination and development of many dangerous clinical diseases, for which there has been little medication so far. To determine whether lactulose has an effect on endotoxemia, we treated experimental, gut-derived endotoxemia using lactulose in vitro and in vivo. The results showed that 55 mg lactulose inactivated the activity of 0.01 mg endotoxin on limulus lysate in vitro, suggesting that lactulose may have a direct anti-endotoxin effect. In vivo study in rats showed that blood endotoxin level was significantly decreased from 78.61 +/- 6.54 pg/ml to 20.26 +/- 2.38 pg/ml (P less than 0.01), and liver damage significantly reduced after lactulose treatment. It is suggested that lactulose can prevent absorbtion of endotoxin from gut and may have an effect on gut-derived endotoxemia. The mechanism of lactulose for treating endotoxemia is discussed.