A prospective study on application of human umbilical cord mesenchymal stem cells combined with autologous Meek microskin transplantation in patients with extensive burns / 中华烧伤杂志

Objective: To investigate the effects of human umbilical cord mesenchymal stem cells (hUCMSCs) combined with autologous Meek microskin transplantation on patients with extensive burns. Methods: The prospective self-controlled study was conducted. From May 2019 to June 2022, 16 patients with extensive burns admitted to the 990th Hospital of PLA Joint Logistics Support Force met the inclusion criteria, while 3 patients were excluded according to the exclusion criteria, and 13 patients were finally selected, including 10 males and 3 females, aged 24-61 (42±13) years. A total of 20 trial areas (40 wounds, with area of 10 cm×10 cm in each wound) were selected. Two adjacent wounds in each trial area were divided into hUCMSC+gel group applied with hyaluronic acid gel containing hUCMSCs and gel only group applied with hyaluronic acid gel only according to the random number table, with 20 wounds in each group. Afterwards the wounds in two groups were transplanted with autologous Meek microskin grafts with an extension ratio of 1∶6. In 2, 3, and 4 weeks post operation, the wound healing was observed, the wound healing rate was calculated, and the wound healing time was recorded. The specimen of wound secretion was collected for microorganism culture if there was purulent secretion on the wound post operation. In 3, 6, and 12 months post operation, the scar hyperplasia in wound was assessed using the Vancouver scar scale (VSS). In 3 months post operation, the wound tissue was collected for hematoxylin-eosin (HE) staining to observe the morphological changes and for immunohistochemical staining to observe the positive expressions of Ki67 and vimentin and to count the number of positive cells. Data were statistically analyzed with paired samples t test and Bonferronni correction. Results: In 2, 3, and 4 weeks post operation, the wound healing rates in hUCMSC+gel group were (80±11)%, (84±12)%, and (92±9)%, respectively, which were significantly higher than (67±18)%, (74±21)%, and (84±16)% in gel only group (with t values of 4.01, 3.52, and 3.66, respectively, P<0.05). The wound healing time in hUCMSC+gel group was (31±11) d, which was significantly shorter than (36±13) d in gel only group (t=-3.68, P<0.05). The microbiological culture of the postoperative wound secretion specimens from the adjacent wounds in 2 groups was identical, with negative results in 4 trial areas and positive results in 16 trial areas. In 3, 6, and 12 months post operation, the VSS scores of wounds in gel only group were 7.8±1.9, 6.7±2.1, and 5.4±1.6, which were significantly higher than 6.8±1.8, 5.6±1.6, and 4.0±1.4 in hUCMSC+gel group, respectively (with t values of -4.79, -4.37, and -5.47, respectively, P<0.05). In 3 months post operation, HE staining showed an increase in epidermal layer thickness and epidermal crest in wound in hUCMSC+gel group compared with those in gel only group, and immunohistochemical staining showed a significant increase in the number of Ki67 positive cells in wound in hUCMSC+gel group compared with those in gel only group (t=4.39, P<0.05), with no statistically significant difference in the number of vimentin positive cells in wound between the 2 groups (P>0.05). Conclusions: The application of hyaluronic acid gel containing hUCMSCs to the wound is simple to perform and is therefore a preferable route. Topical application of hUCMSCs can promote healing of the autologous Meek microskin grafted area in patients with extensive burns, shorten wound healing time, and alleviate scar hyperplasia. The above effects may be related to the increased epidermal thickness and epidermal crest, and active cell proliferation.

Influence of age on median lethal burn area of burn patients / 中华烧伤杂志

<p><b>OBJECTIVE</b>To discuss the influence of age on the LA50 (the burn area lethal to 50% of patients) of burn patients.</p><p><b>METHODS</b>(1) Twenty-three thousand and seventy-three burn patients hospitalized in our center from December 1958 to December 2004 were enrolled, and they were divided into 25 age groups. LA50 values of total and full-thickness burn areas of patients in each age group were computed with probit regression method with Probit analysis of SPSS 11.0. (2) Those age groups with similar LA50 values were merged into one age group; thus 4 new age groups were formed. LA50 and its 95% confidence interval (CI) of total and full-thickness burn areas of patients in each age group were computed respectively. (3) All the patients were divided into group A (admitted from 1 December 1958 to 31 December 1983) and group B (admitted from 1 January 1984 to 31 December 2004) according to the admission time. LA50 and its 95% CI of total and full-thickness burn areas of patients in each age group of groups A and B were computed respectively.</p><p><b>RESULTS</b>(1) LA50 values of total and full-thickness burn areas of patients among the 25 age groups were low in age groups younger than or equal to 5 years, which increased in age groups older than 5 years, distinctly higher in age groups older than 15 years, and they became lower in age groups older than 60 years. (2) LA50 values of total and full-thickness burn areas of patients in the 4 merged age groups were lowest in age groups older than 60 years (50.90% TBSA) and younger than or equal to 5 years (35.81% TBSA), and highest in age group older than 15 years and younger than or equal to 60 years (89.38% and 59.22% TBSA). There were statistically significant differences in LA50 of total and full-thickness burn areas of patients among 4 merged age groups [with 95% CI values of LA50 of total burn areas of patients in age groups ranging from young to old respectively (56.87 to 64.69)%, (64.46 to 74.36)%, (85.89 to 93.37)%, (44.55 to 60.73)% TBSA; with 95% CI values of LA50 of full-thickness burn areas of patients in age groups from young to old respectively (32.67 to 39.69)%, (40.86 to 50.41)%, (55.27 to 63.85)%, (32.46 to 54.86)% TBSA]. (3) LA50 values of total and full-thickness burn areas of patients in group B (98.94% and 73.23% TBSA) were significantly higher than those in group A (69.61% and 39.79% TBSA). There were differences in LA50 values of patients among different age groups in both group A and group B. The variation trend of LA50 values of patients among the 4 age groups in groups A and B was almost the same. Except for LA50 of total burn areas of patients in age group older than 5 years and younger than or equal to 15 years and LA50 of full-thickness burn areas of patients in age group older than 60 years, there were statistically significant differences in the LA50 of total and full-thickness burn areas of the other patients between group A and group B [with 95% CI of LA50 of total burn areas of patients of younger than or equal to 5 years, older than 15 years and younger than or equal to 60 years, and older than 60 years respectively (48.38 to 56.07)% and (68.68 to 81.35)% TBSA, (75.91 to 84.89)% and (97.09 to 110.45)% TBSA, (30.08 to 45.08)% and (60.67 to 102.69)% TBSA; with 95% CI of LA50 of full-thickness burn areas of patients of younger than or equal to 5 years, older than 5 years and younger than or equal to 15 years, older than 15 years and younger than or equal to 60 years respectively (27.48 to 34.69)% and (42.09 to 54.03)% TBSA, (34.78 to 46.43)% and (49.62 to 69.47)% TBSA, (43.98 to 51.77)% and (66.43 to 77.99)% TBSA].</p><p><b>CONCLUSIONS</b>Age is one of the important factors that influence the LA50 of burn patients. LA50 in different age groups increases with the development of medical technology; however, the influence of age on LA50 is not visibly changed by the advance of treatment.</p>

Evaluation of allogenic complement-regulating proteins in the peripheral blood cells of chimeric rat models harboring human cord blood stem cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze the mechanisms of surrogate tolerogenesis induced by chimeric donors.</p><p><b>METHODS</b>Hematopoietic stem cells (HSCs) from human cord blood were transplanted into fetal rats via intrauterine injection and infused into the liver of the neonatal rats to establish chimeric rat models with human HSCs. Four weeks after birth, flow cytometry was performed to analyze the percentages of human CD45 (hCD45), CD55 (hCD55) and CD59 (hCD59)-positive cells in the peripheral blood cells of the chimeric rats. The distributions of hCD55- and hCD59-positive cells in different hCD45/SSC gating regions were observed. The resistance of the peripheral blood lymphocytes to complements-mediated cytolysis was assessed by complement-dependent cytotoxicity (CDC) test in the chimeric rats and compared with that in control rats. The correlation between CDC and the human complement-regulating proteins in the chimeric rats were analyzed statistically.</p><p><b>RESULTS</b>On hCD45/SSC gating, the percentages of hCD55- and hCD59-positive cells in hCD45-positives region were (53.69-/+18.23)% and (31.8-/+27.5)%, accounting for (2.0-/+1.32)% and (0.76-/+0.56)% of the total cell population, respectively, which were significantly lower than the cell percentages in the extensive region (t=2.71, P=0.043 and t=3.64, P=0.015). The cytolytic rate of PBLs incubated with normal human serum was (22.32-/+15.10)% in the chimeric rats, significantly lower than that in the non-chimeric rats [(60.7-/+22.65)%, t=4.16, P<0.001). In the chimeric rats, hCD55-positive cell percentage was inversely correlated in the peripheral blood karyocytes the cytolysis rate in CDC (r=-0.679, P=0.031), and positively correlated to hCD45-positive cell percentage (r=0.658, P=0.038).</p><p><b>CONCLUSION</b>The hCD45-positives region is the cluster of chimeric human cells expressing human complement-regulating proteins. The peripheral blood lymphocytes from chimeric donor can resist the cytolysis mediated by human complement. The presence of allogenic CD55 and CD59 antigens in chimeric donors may be the basis of surrogate tolerogenesis for xenotransplantation.</p>

Categorization of burn severity / 中华烧伤杂志

<p><b>OBJECTIVE</b>To seek a new method for the categorization of burn severity.</p><p><b>METHODS</b>Burn patients hospitalized in our center from December of 1958 to December of 2004 were enrolled in the study, and they were divided into different age groups according to same mortality, then the patients in each group were subdivided into 4 groups according to the burn severity: i.e., mild burns, moderate burns, severe burns, serious severe burns. The total burn area, the number of cases, the mortality, and the area of DI degree burns were statistically analyzed in each subgroup, and the scope in total burn area and area of III degree burns were taken as standards to define the degree of burns. The logistic regression equation was established with probability of death as the variable, and age, total burn area, burn area of different degrees as concomitant variables to form a logistic regression formula. It was used to predict the probability of death of patients hospitalized in 2005, 50 as to check whether the corresponding indices of these patients were consistant with above standard of categorization into degrees, and to judge hum severity of the patients who had concomitant inhalation injury, severe associated injury, or those with serious disease before burns.</p><p><b>RESULTS</b>The patients were divided into three groups: less than 2 years of age (including 2 years of age), 2 to 55 years of age(including 55 years of age), and older than 55 years of age groups. The classification standard of burn area was shown in table 2 of the article. The probability of death and corresponding indices predicted hy the logistic regression equation were highly coincident with our standard. Patients with moderate inhalation injury could be regarded as patients with severe or most severe burns, while severity of those with mild inhalation injury could be determined by burn area alone.</p><p><b>CONCLUSION</b>The logistic regression equation is a good method to predict the severity of burn patients, with reasonable age specificity grouping, and accurate and practical scoring of division for corresponding burn severity.</p>

Preliminary study on immunologic tolerance for hetero-skin graft induced by chimeric donors / 中华烧伤杂志

<p><b>OBJECTIVE</b>To explore the feasibility of transplanting the skin from chimeric rats to rabbits.</p><p><b>METHODS</b>Chimeric rats were produced by transplanting the haematopoietic stem cells (HSCs) from rabbit marrows into fetal rats in uterus and followed by injecting the HSCs into the livers of the rats at newborn stage. After six weeks, the skin from chimeric rats was transplanted to the rabbits. In group A, the skin grafts from chimeric rat donors were transplanted to the HSCs donating rabbits, with the skin from non-chimeric rat to normal rabbits were used as control. In group B, the skin grafts from chimeric and non-chimeric rats were transplanted to the HSCs donating rabbits at the same time. Gross observation and the surviving time of heterogenic-skin graft were observed. The wound healing time was also recorded.</p><p><b>RESULTS</b>In group A, the surviving time and the wound healing time of non-chimeric grafts were (9.3 +/- 1.8) days and (20.9 +/- 2.1) days, respectively, while those in chimeric grafts were (15.1 +/- 2.6) and (18.5 +/-1.3) days, respectively. In group B, the surviving time and the wound healing time of non-chimeric grafts were similar to those of group A. Compared with those in non-chimeric grafts, the surviving time of chimeric grafts in both groups were prolonged (P < 0.01), and the wound healing time shortened (P < 0.05 or 0.01). Most of the wounds healed quickly after rejection of chimeric grafts, while the wounds with non-chimeric grafts were re-opened with exudation and some necrotic tissue.</p><p><b>CONCLUSION</b>Immunologic tolerance for skin graft can be induced by the skin from chimeric donors, which can prolong the surviving time of skin grafts and shorten the wound healing time.</p>