[Feasibility study on the preparation of novel negative pressure materials for constructing new matrix of full-thickness skin defect wounds in rats].

Objective: To explore the feasibility on the preparation of novel negative pressure materials for constructing new matrix of full-thickness skin defect wounds in rats. Methods: The experimental research method was applied. The microstructure of polyurethane foam dressing which was commonly used in negative pressure treatment was observed under scanning electron microscope, and its pore diameter was detected (n=5). Polycaprolactone (PCL) and polybutylene succinate (PBS) were used respectively as raw materials for the preparation of PCL and PBS negative pressure materials by melt spinning technology, with the measured pore diameter of polyurethane foam dressing as the spinning spacing at the spinning rates of 15, 25, and 35 mm/s, respectively. The microstructures of the prepared negative pressure materials were observed under scanning electron microscope, and their fiber diameters were measured. The tensile strength and tensile modulus of the prepared negative pressure materials and polyurethane foam dressing were measured by tensile testing machine and composite testing machine, respectively (n=5), to screen the spinning rate for subsequent preparation of negative pressure materials. Human skin fibroblasts (Fbs) in logarithmic growth phase were co-cultured with PCL negative pressure material and PBS negative pressure material prepared at the selected spinning rate, respectively. After 1, 4, and 7 day (s) of co-culture, the cell activity and adhesion in the materials was detected by living/dead cells detection kit, and the cell proliferation level in the materials was detected by cell counting kit 8 method (n=5). A full-thickness skin defect wound was prepared on the back of 18 5-6 weeks old Sprague-Dawley rats (gender unlimited). Immediately after injury, the injured rats were divided into PCL+polyurethane group, PBS+polyurethane group, and polyurethane alone group according to the random number table (with 6 rats in each group). The wounds were covered with materials containing corresponding component and performed with continuous negative pressure suction at the negative pressure of -16.7 kPa. The wound tissue along with materials directly contacted to the wound (hereinafter referred to as wound specimens) were collected from 3 rats in each group after 7 and 14 days of negative pressure treatment (NPT), respectively. The growth of granulation tissue and the attachment of material to wound surface were observed after hematoxylin-eosin staining, the collagen fiber deposition was observed after Masson staining, and CD34 and interleukin-6 (IL-6) positive cells were detected and counted by immunohistochemical staining. Data were statistically analyzed with one-way analysis of variance, analysis of variance for factorial design, least significant difference-t test, Kruskal-Wallis H test, Mann-Whitney U test, and Bonferroni correction. Results: The microstructure of polyurethane foam dressing was loose and porous, with the pore diameter of (815±182) µm. The spinning spacing for the subsequent negative pressure material was set as 800 µm. The microstructures of PBS negative pressure material and PCL negative pressure material were regular, with vertically interconnected layers and continuous fibers in even thickness, but the fibers of PBS negative pressure material were straighter than those of PCL negative pressure material. There was no obvious difference in the microstructure of negative pressure materials prepared from the same raw material at different spinning rates. The fiber diameters of PCL negative pressure materials prepared at three spinning rates were similar (P>0.05). The fiber diameters of PBS negative pressure materials prepared at spinning rates of 25 mm/s and 35 mm/s were significantly smaller than the fiber diameter of PBS negative pressure material prepared at the spinning rate of 15 mm/s (with t values of 4.99 and 6.40, respectively, P<0.01). Both the tensile strength and tensile modulus of PCL negative pressure materials prepared at three spinning rates were similar (P>0.05). The tensile strength of PBS negative pressure materials prepared at spinning rates of 15 mm/s and 25 mm/s was significantly lower than that of PBS negative pressure materials prepared at the spinning rate of 35 mm/s (with t values of 9.20 and 8.92, respectively, P<0.01), and the tensile modulus was significantly lower than that of PBS negative pressure materials prepared at the spinning rate of 35 mm/s (with t values of 2.58 and 2.47, respectively, P<0.05). Subsequently, PCL negative pressure material was prepared at the spinning rate of 35 mm/s, and PBS negative pressure material was prepared at the spinning rate of 15 mm/s. After 1, 4, and 7 day (s) of co-culture, the number of human skin Fbs that adhered to PCL negative pressure material and PBS negative pressure material increased with time, and there was no significant difference between the two materials. After 1 and 7 day (s) of co-culture, the proliferation levels of human skin Fbs between the two negative pressure materials were similar (P>0.05). After being co-cultured for 4 days, the proliferation level of human skin Fbs in PBS negative pressure material was significantly higher than that in PCL negative pressure material (t=6.37, P<0.01). After 7 days of NPT, the materials were clearly identifiable and a small amount of collagen fibers were also observed in the wound specimens of rats in the three groups; a small amount of granulation tissue was observed in the wound specimens of rats in polyurethane alone group. After 14 days of NPT, a large number of granulation tissue and collagen fibers were observed in the wound specimens of rats in the three groups; the materials and wound tissue in the wound specimens of rats in PCL+polyurethane group could not be clearly distinguished. After 7 and 14 days of NPT, the collagen fibers in the wound specimens of rats in polyurethane alone group were denser than those in the other two groups. After 7 days of NPT, the number of CD34 positive cells in the wound specimens of rats in PBS+polyurethane group was 14.8±3.6 per 400 times visual field, which was significantly less than 27.8±9.1 in polyurethane alone group (t=3.06, P<0.05); the number of IL-6 positive cells was 60 (49, 72), which was significantly more than 44 (38, 50) in polyurethane alone group (Z=2.41, P<0.05). After 14 days of NPT, the number of IL-6 positive cells in the wound specimens of rats in PBS+polyurethane group was 19 (12, 28) per 400 times visual field, which was significantly more than 3 (1, 10) in PCL+polyurethane group and 9 (2, 13) in polyurethane alone group (with Z values of 2.61 and 2.40, respectively, P<0.05). Conclusions: The prepared PCL negative pressure material and PBS negative pressure material have good biocompatibility, and can successfully construct the new matrix of full-thickness skin defect wounds in rats. PCL negative pressure material is better than PBS negative pressure material in general.

[Study on the relationship between uncertainty in illness and caregiving burden in family members of patients with chronic wounds].

Objective: To investigate the current status of uncertainty in illness and caregiving burden in family members of patients with chronic wounds, and to analyze the relationship between them. Methods: A total of 180 patients with chronic wounds admitted to the Department of Emergency of our hospital from October 2017 to March 2018, conforming to the study criteria, were selected by adopting the convenience sampling method. Then one family member who took care of the patients for the longest time and conformed to the study criteria were included in this cross-sectional survey. General Information Questionnaire made by the authors was conducted to investigate the demographic data and wounds of patients, and demographic data of family members. Chinese version of Parent Perception of Uncertainty Scale-Family Member (PPUS-FM) and Caregiver Burden Inventory (CBI) were used to investigate the uncertainty in illness and caregiving burden. Data were processed with multiple linear regression analysis and partial correlation analysis. Results: The effective recovery rate of questionnaire was 91.7% (165/180). (1) The ages of patients were (71±17) years. Among them, there were 89 males and 76 females. The course of chronic wounds was 0.5 to 120.0 months. The wounds were mainly primary occurrence (86.1%, 142 patients), and the main type of wound was pressure ulcer (43.6%, 72 patients). Fifty-seven patients (34.5%) had wound infection. The ages of family members were (56±13) years, and 61.8% (102 people) of them were female. Their daily time of taking care of patients was (10±8) h. (2) The total scores of PPUS-FM of family members were 33 to 125 (88±17) points, mainly in medium level, in which the item score of unpredictability dimension was the highest. (3) The total scores of CBI of family members were 7 to 79 (43±14) points, in which the item score of time-dependence burden dimension was the highest. (4) Uncertainty in PPUS-FM could independently influence 10% of the total variation of caregiving burden in family members of patients (t=3.18, P<0.01). (5) The total scores of PPUS-FM of family members were in significantly positive correlation with the total scores of CBI and scores of physical burden, emotional burden, and social burden, respectively (r=0.33, 0.32, 0.25, 0.36, P<0.05 or P<0.01), while there was no obvious correlation between total scores of PPUS-FM of family members and time-dependence burden/developmental burden (r=0.14, 0.16, P>0.05). Conclusion: There is positive correlation between uncertainty in illness and caregiving burden.