Optimal site and amount of splenic tissue for autotransplantation.

Clinical and basic studies have documented a high susceptibility to pneumococcal infection in asplenic humans and animals. It has been suggested that autotransplantation of splenic tissue might be a method of providing host resistance when total splenectomy is necessary. However, the effect of splenic autograft has remained controversial. This study was performed to evaluate the most effective site and amount of splenic autograft using rats. Rats were divided into five groups for the purpose of determining the site of splenic autotransplantation: splenectomy, sham operation, implantation into the omental pouch, intraperitoneal implantation, and intramuscular implantation. For determining the amount for autotransplantation, the rats were divided into seven groups: splenectomy, sham operation, and implantations of 25, 50, 100, 200, or 300 mg of splenic tissue. All animals were challenged with Streptococcus pneumoniae type 6, 16 weeks after surgery. Howell-Jolly bodies appeared postsplenectomy, but disappeared in the implanted rats 16 weeks after the operation. Histologically, the implanted tissue was indistinguishable from that of a normal spleen. Pneumococcal clearance from the bloodstream and survival rate were significantly higher in rats implanted in the omental pouch as compared with splenectomized rats. Intraperitoneal and intramuscular implanted rats did not show a significant difference from the splenectomized rats. More than 50% of splenic tissue for autograft showed a significant increase in pneumococcal clearance and survival rate as compared with that of splenectomized rats. It was suggested that the most effective site of autotransplantation is the omental pouch and approximately 50% of the whole spleen would be necessary for prevention from sepsis.     

Does survival depend on the amount of autotransplanted splenic tissue?

Susceptibility to Streptococcus pneumoniae infection was studied in 11 groups of rats allocated to sham operation, splenectomy, or splenic autotransplantation of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the removed spleen. Three months later, all rats were exposed intravenously to type 1 Streptococcus pneumoniae (median lethal dose, LD50, for control group). Survivors were killed 13 days after the bacterial challenge. Autopsy showed that more splenic tissue was recovered in rats that received less than 50% splenic tissue compared with those that received 50% or more. More survivors were found among sham-operated rats (47.5%; 95% confidence intervals, 32 to 68) and rats that had 40% splenic tissue implanted (35%; confidence interval, 20 to 54) or those that were found to have regenerated 40% splenic tissue. We conclude that 40% of the spleen should be autotransplanted to protect the rat optimally against infection after splenectomy.     

Decreased phagocytic capacity of autotransplanted splenic tissue

Background: Asplenic patients have an increased risk of infections. Operations such as autotransplantation have been proposed to restore functional splenic tissue after splenectomy, but the protective value of this tissue is unclear. Immune responses such as production of antibody remain impaired in humans and animals even when such tissue is present, and clearance of particles from the blood is reported to be less efficient than by normal spleen tissue. The present study investigated the phagocytic capacity of cells in the regenerated tissue in vitro, free of the confounding effects of hepatic clearance. Methods: Single cell suspensions were prepared from splenic tissue from rats 6 months after splenic autotransplantation or sham operation. Phagocytosis of killed, fluorescein‐labelled bacteria was measured by flow cytometry. Results: Autotransplanted tissue contained fewer phagocytic cells than normal tissue, and these cells phagocytosed less per cell. Phagocytosis by spleen cells was dependent on heat‐labile opsonic factors. Conclusions: Autotransplanted splenic tissue does not restore the phagocytic capacity lost following splenectomy.     

Improved survival with splenic autotransplantation and fibronectin therapy following endotoxin administration in rats

The risk of overwhelming infections is greatly increased after splenectomy. In this experimental study in rats, we investigated whether the administration of fibronectinrich cryoprecipitate can improve the survival rate of splenectomized autotransplanted rats subjected to an intravenous challenge with endotoxin. Inbred Lewis rats were divided into four groups: A, splenectomy; B, splenectomy + splenic autotransplantation; C, splenectomy, splenic autotransplantation + fibronectin treatment, and D, sham. Five months after surgery, rats were challenged intravenously with Escherichia coli endotoxin. Immunoglobulin (IgG, IgM, IgA), complement and fibronectin levels were measured before surgery and endotoxin challenge, and 48 h after endotoxin challenge. The survival rate of splenectomized rats was not significantly improved by autotransplantation of splenic tissue, but was significantly (p less than 0.05) improved by autotransplantation and fibronectin treatment. The levels of fibronectin, immunoglobulins and/or complements were significantly decreased after endotoxin challenge in control and in autotransplanted fibronectin-treated rats. The survival improvement of autotransplanted rats treated by fibronectin is probably due to increased endotoxin phagocytosis and clearance.     

Regeneration of splenic remnants after partial splenectomy in rats

Splenic regeneration in the rat was measured after removal of 25, 50, or 75% of the spleen, 50% of the spleen with autotransplantation of the excised portion, and splenectomy with autotransplantation of 50% of the spleen. Splenic growth in rats undergoing sham splenectomies served as a control. Splenic mass at 6 weeks and 4 months after surgery was directly related to the remnant size. “Normalized” spleen weights (measured as grams of splenic tissue per 100 grams of rat weight) after 25, 50, and 75% splenectomy were 57, 41, and 38% of controls at 6 weeks, and 77, 71, and 44% of controls at 4 months. All differences were significant at P < 0.03 except those between 50 and 75% splenectomy at 6 weeks, and between 25 and 50% splenectomy at 4 months. A comparison of autotransplanted splenic mass after total splenectomy with that after 50% splenectomy (0.042 ± 0.005 and 0.025 ± 0.004, respectively, at 6 weeks) demonstrated that an intact subtotal spleen inhibited significantly regeneration of the autotransplanted spleen. The effect of autotransplanted splenic tissue on regeneration of a splenic remnant was little to none at 4 months.     

SPLENIC AUTOTRANSPLANTATION IN RABBITS：NO RESTORATION OF RESPONSE TO HOST DEFENSE

Objective:To explore the effectiveness of splenic tissue autotransplantation in restoring host defense. Methods: Rabbits were divided into three groups,Sham Operation(SO), Splenic Autotransplantation(SA)and Total Splenectomy(TS) ,and dynamic changes in histology and immunology were observed for over 24 weeks. Results: Histologic study shows that the white pulps were poorly developed and central arterioles disappeared in the regenerated splenic tissue. The weight of regenerated spleens recovered six months later in SA was 11% of that in SO, and was significantly reduced comparing with the implanted weight(P<0.05).Tere were no significant difference in the number of T lymphocytes and the levels of serum lysozyme among the three groups. A poor antibody response by the rabbits of SA and TS as compared to those of SO was noted after the primary intravenous administration with sheep red blood cells. After the challenge with type 3 pneumococci intravenously, pneumococcal clearance from bloodstream in SA did not dif     

自体移植脾巨噬细胞C_(3b)、Fc受体及蛋白质表达的实验研究

目的　探讨自体脾组织移植后的功能状况。方法　采用小鼠进行自体脾组织网膜内移植 ,术后 6个月切取移植脾组织 ,检测巨噬细胞的Fc、C3b受体及蛋白表达。结果　自体移植脾巨噬细胞Fc受体的含量与原位脾相近 ,C3b受体的功能正常 ;蛋白质的表达与原位脾相同。结论　大网膜内自体移植脾组织的功能在细胞水平是正常的 ,移植脾组织具有原位脾的功能。     

Response to immunization after partial and total splenectomy

Survival after infection from Streptococcus pneumoniae in both animals and man is influenced by the amount of splenic tissue. We investigated the effect of differences in splenic weight upon the antibody response to immunization and the effect of immunization upon survival after pneumococcal challenge. Young Sprague-Dawley rats had either sham operation, hemisplenectomy, splenectomy with splenic autotransplantation, or total splenectomy. Nine weeks later, rats were immunized with a heat- and formalin-killed type-specific pneumococcal vaccine. Antibody response measured by radioimmunoassay was similar in all operative groups and was significantly higher than in nonimmune rats (P less than 0.01). Splenic weight was less after hemisplenectomy or autotransplantation than in sham-operated animals (P less than 0.01). Immunization improved survival after live pneumococcal challenge in rats that had autotransplantation and total splenectomy (P less than 0.001). Our results demonstrate that splenic weight does not affect the antibody response to pneumococcal immunization in rats. Immunization improves survival after bacterial challenge in susceptible animals and minimizes the detrimental effect of reduction in splenic mass.     

自体脾组织移植后病理学变化的实验研究

目的　研究自体脾组织移植后不同时相点病理形态学变化规律。　方法　健康Wistar大鼠 5 6只 ,雌雄不限 ,体重 10 0～ 12 0 g ,随机分为 7组 ,每组 8只中又设脾切除自体组织大网膜内脾移植组 5只 ,假手术组 3只 ,分别于术后 7、14、3 0、60、90、12 0、180d取脾组织 ,光镜、透射电镜观察。　结果　移植脾组织之重量在术后 7d最轻 ,为 0 .0 72 g ,其后逐渐增加 ,180d时为 0 .5 11g ,各时相点之间有明显差异 (P <0 .0 5 )。病理检查提示移植脾组织经历急性期、缓解期、修复期三个病理时期 ,逐步恢复并接近正常的组织结构。　结论　自体脾组织大网膜内移植术是简便有效的脾移植方法。自体移植脾组织再生过程可分为 :急性期、缓解期与修复期     

Serum antibody responses to pneumococcal vaccine after splenic autotransplantation

Immunization with pneumococcal capsular polysaccharide vaccines is advocated after splenectomy; however, experimental and clinical data suggest an impaired antibody response in splenectomized individuals. This study examined the value of splenic autotransplantation at various sites in augmenting the antibody response to Type III pneumococcal capsular polysaccharide in mice immunized 3 months after operation. Splenectomy resulted in impaired antibody responses compared to sham-operated mice (p less than 0.001) using an enzyme-linked immunosorbent assay. Mice with intraperitoneal splenic autotransplants, but not mice with subcutaneous or intramuscular transplants, had greater antibody responses compared to splenectomized mice (p less than 0.05). Antibody responses were elevated only in mice autotransplanted with 50% or more of the original splenic mass. Since autotransplantation of splenic tissue augments the antibody response to pneumococcal capsular polysaccharides, the combination of splenic autotransplantation and pneumococcal vaccination may confer more protection than either modality alone in individuals who must undergo splenectomy.     

Immune cell subpopulations in regenerated splenic tissue in rats.

BACKGROUND: Asplenic patients have an increased risk of infections. Operations such as autotransplantation or splenic artery ligation have been suggested to ensure retention of functional splenic tissue after splenectomy, but their protective value is unclear. Immune responses, such as production of antibody, remain impaired in humans and animals even when such tissue is present, and phagocytosis is less efficient than by normal spleen tissue. In the present study the cellular composition of regenerated tissue is determined. METHODS: Splenic tissue was obtained from rats 6-9 months after splenic autotransplantation, splenic artery ligation or sham operation. The lymphocyte and macrophage subpopulations were labelled using a panel of monoclonal antibodies and analysed by flow cytometry. RESULTS: Both the total number of cells and the number of cells per gram of tissue were significantly reduced. There was a substantial reduction in the percentage of some of the cells examined (CD4+ and CD8+ T lymphocytes subsets), but not all (B lymphocytes, ED1+ and ED2+ macrophages, OX2+ and OX6+ cells). CONCLUSIONS: The reduction in the T lymphocyte subsets in regenerated splenic tissue compared with the normal spleen might explain the immunological dysfunction which persists after splenic autotransplantation. The reduction in the number of macrophages may be responsible for the alteration in phagocytic efficiency of regenerated splenic tissue.     

Splenic phagocytic function after partial splenectomy and splenic autotransplantation

We investigated splenic reticuloendothelial activity after splenic preservation procedures to determine their effect upon the phagocytic function of the spleen. We performed the following procedures in Sprague-Dawley rats: sham laparotomy, total splenectomy, hemisplenectomy, subtotal splenectomy, or total splenectomy with intraperitoneal splenic autotransplantation. At nine weeks after operation, phagocytic function of the spleen was determined by measuring radiocolloid uptake. Mean (+/- SEM) splenic phagocytic indices for sham laparotomy (41.2 +/- 2.9), hemisplenectomy (44 +/- 2.9), and subtotal splenectomy (43.2 +/- 5.2) were similar; however, the phagocytic index was reduced markedly after autotransplantation (15.8 +/- 2.2). These data demonstrate that the phagocytic function of the spleen after hemisplenectomy and subtotal splenectomy correlates highly with the weight of the splenic remnant; however, phagocytic function after autotransplantation remains reduced even after accounting for differences in splenic weight.     

Splenic autotransplantation provides protection against fatal sepsis in young but not in old rats.

Splenectomy increases the risk of contracting infections with high mortality. Thus, splenic tissue should be repaired orthotopically whenever possible. If all attempts fail, splenic autotransplantation might be a suitable method for splenic salvage. The protective function of such transplants in adults has been questioned, leading to a decreased frequency of splenic autotransplantations. However, the regeneration of splenic tissue is better in the young organism than in the old, suggesting that the protection provided by regenerated splenic tissue might be more reliable in children than in adults. In addition, children are at a higher risk in the case of overwhelming postsplenectomy sepsis. The protection warranted by regenerated splenic tissue after autotransplantation at different ages was examined using a highly standardized animal model. Sham operation, splenectomy, and splenic autotransplantation were performed on adult, weanling, and newborn rats, and Streptococcus pneumoniae was applied intranasally 9 months after the operation. After pneumococcal challenge about 80% of the splenectomized animals in the different age groups died of infection, whereas only 20% of the sham operated rats died. Regenerated splenic tissue resulting from splenic autotransplantation performed on adult or weanling rats demonstrated no protective function. However, in newborn rats with transplanted splenic tissue, both survival rate and survival time were increased significantly. Determination of lymphocyte subsets in the blood did not allow the protective role of splenic transplants to be predicted. This study indicates that disappointing results of splenic autotransplantation in adult patients should not lead to false pessimism about the role of this operation in children.     

Relative merits of partial splenectomy, splenic reimplantation, and immunization in preventing postsplenectomy infection.

Partial splenectomy, splenic autotransplantation, and immunization with pneumococcal vaccine have been reported to protect patients against overwhelming postsplenectomy infection, and this study was undertaken to evaluate these therapeutic alternatives. For this purpose 136 rats were divided into experimental groups: 34 controls, 34 splenectomy, 34 partial splenectomy, and 34 splenic autotransplantation animals. Five weeks after operation, two-thirds of the animals were immunized with killed pneumococci. The effects of operation and immunization were studied by challenging the animals intravenously with pneumococci. Pneumococcal antibody titers were determined, and phagocytic uptake of pneumococci by the spleen and liver was measured. Immunization impressively increased the survival rate in all groups. At low-challenge doses autotransplantation prolonged survival. At higher-challenge doses only partial splenectomy increased survival. Partial splenectomy and control animals had higher antibody titers than did splenectomy and autotransplantation rats. Animals with the highest antibody titers had the greatest splenic and hepatic phagocytic uptake of pneumococci. Partial splenectomy was more efficient in removing pneumococci than was autotransplantation. Thus immunization is one of the most important factors contributing to survival after splenectomy. Partial splenectomy is preferable to splenic autotransplantation because it is associated with higher antibody titers after immunization, better pneumococcal splenic uptake, and improved survival rates.     

自体移植脾组织VEGF、KDR表达与血管再生的实验研究

目的 研究自体移植脾组织血管再生及VEGF、KDR表达规律，阐明VEGF、KDR对移植脾组织血管再生的调控作用，为脾脏外科临床及实验研究提供理论依据。方法 健康Wistar大鼠70只，体重100—120g，随机分为7组，每组10只中又设脾切除自体脾移植组5只，假手术组5只，分别于术后7，14，30，60，90，120，180d进行：(1)自体移植脾组织病理学检测；(2)大鼠行主动脉插管灌注墨汁，光镜观测再生血管并采用图像分析测定其密度；(3)免疫组化抗VEGF、KDR抗体染色，图像分析定量，阐明其表达规律及与血管再生的关系。结果 (1)自体脾组织移植术后7d即有血管从大网膜向脾组织内伸展，移植脾组织内血管密度逐渐增大，至术后180d血管再生接近正常；(2)自体脾组织移植术后7d、14d，VEGF、KDR阳性染色细胞密度迅速升高，术后60d达高峰，以后逐渐降低，至术后180d VEGF、KDR阳性染色细胞密度趋向正常。结论 自体脾组织大网膜内移植术是简便有效的脾移植方法；移植脾组织新生血管由大网膜再生而来；术后移植脾组织内VEGF、KDR表达量升高，促进血管形成，血管再生完成后恢复正常水平。     

Splenic autotransplantation: determination of the optimum amount required for maximum survival

Splenic salvage in cases of traumatic or iatrogenic injuries may require autotransplantation of splenic fragments when splenorrhaphy or partial splenectomy is not possible. There are no studies which address the issue concerning the optimal amount of spleen to be transplanted in order to yield maximal survival in a model of pneumococcal sepsis. This study uses a Sprague-Dawley rat model to attempt to clarify this issue. Animals were divided into seven groups: control, total splenectomy, 25, 40, 60, 80, and 100% omental pouch autotransplantation. These animals were challenged with intravenous Streptococcus pneumonia Type I after 24 weeks, and mortality and blood culture results were monitored. Transplants were recovered and weights were compared with the weights originally transplanted. Survival and blood culture results were seen to improve in a linear quantitative fashion as the amount of spleen autotransplanted increased up to 80%, after which no further improvement was seen. This data supports the autotransplantation of 80% of the spleen in the Sprague-Dawley rat as the optimum amount to achieve maximal survival in a model of pneumococcal sepsis.     

IMMUNE CELL SUBPOPULATIONS IN REGENERATED SPLENIC TISSUE IN RATS

Background : Asplenic patients have an increased risk of infections. Operations such as autotransplantation or splenic artery ligation have been suggested to ensure retention of functional splenic tissue after splenectomy, but their protective value is unclear. Immune responses, such as production of antibody, remain impaired in humans and animals even when such tissue is present, and phagocytosis is less efficient than by normal spleen tissue. In the present study the cellular composition of regenerated tissue is determined. Methods : Splenic tissue was obtained from rats 6–9 months after splenic autotransplantation, splenic artery ligation or sham operation. The lymphocyte and macrophage subpopulations were labelled using a panel of monoclonal antibodies and analysed by flow cytometry. Results : Both the total number of cells and the number of cells per gram of tissue were significantly reduced. There was a substantial reduction in the percentage of some of the cells examined (CD4⁺ and CD8⁺ T lymphocytes subsets), but not all (B lymphocytes, ED1⁺ and ED2⁺ macrophages, OX2⁺ and OX6⁺ cells). Conclusions : The reduction in the T lymphocyte subsets in regenerated splenic tissue compared with the normal spleen might explain the immunological dysfunction which persists after splenic autotransplantation. The reduction in the number of macrophages may be responsible for the alteration in phagocytic efficiency of regenerated splenic tissue.     

Pulmonary antipneumococcal defenses after hemisplenectomy

Conservative splenic surgery such as partial splenectomy is advocated for splenic injuries, since splenectomy predisposes individuals to overwhelming sepsis with encapsulated organisms, of which Streptococcus pneumoniae is the most frequently isolated. The respiratory route is argued to be the most likely portal of entry of pneumococci; however, little data exist on the interaction of the spleen and pulmonary defense mechanisms against pneumococcal invasion. We studied the effect of splenectomy, 50% splenectomy (hemisplenectomy), 25% splenectomy, and sham operation on in vivo clearance of live pneumococci from the lungs of male CD-1 mice following an aerosol challenge of pneumococci. Splenectomy impaired pneumococcal clearance from mouse lung pairs and allowed for increased translocation of live pneumococci to tracheobronchial lymph nodes compared to sham-operated controls. Preservation of splenic mass by partial splenectomy improved lung clearance and allowed for fewer bacteria to be cultured from tracheobronchial lymph nodes compared to splenectomized animals. Clearance of live pneumococci from the lungs and survival were directly proportional to the amount of splenic tissue remaining. Splenic factors probably exist which regulate reticuloendothelial cell function throughout the host. Maintaining adequate splenic mass, therefore, is an important consideration when operating for splenic trauma.     

The immunological studies on the splenectomy and the splenic autotransplantation in BALB/C mice

Recently, it has been demonstrated that the severe infectious diseases are often caused after splenectomy. The significance of spleen on humoral immunity has been pointed out, however the alterations of cellular immunity by splenectomy has not yet been investigated sufficiently. In this study, the effects of splenectomy on the immunological aspects were examined. And the reconstruction of immunological responses by the splenic autotransplantation was also examined. The results obtained were as follows. The antibody titers against SRBC of the splenectomized groups continued to be apparently lower than those of sham-operated groups. The IgM of the splenectomized groups showed lower values than that of the sham-operated groups, but concerning IgG, no distinct differences were noticed among these two groups. On the proliferation of peripheral lymphoid cells, the splenectomized groups from 4th week later showed a higher response than the sham operated groups. The splenic autotransplanted groups showed a similar response to the sham operated ones in the antibody production against SRBC, and the proliferations of lymphocytes. The splenic autotransplantation might be suggested to be a worthy application.     

Phagocyte function after splenic autotransplantation

This study was designed to examine the role of splenectomy and autotransplantation with regard to the leukocyte/differential cell counts and the function of peripheral blood phagocytes. Eleven groups of 40 Wistar male rats in each group either underwent total splenectomies or sham operations. The splenectomized groups underwent autotransplantations with 10% through 90% of the weight of the intact spleen. The leukocyte count and the oxidative burst response of the blood leukocytes were measured in each group. It was shown that a total splenectomy did not alter the leukocyte/differential cell counts. Furthermore, the blood picture remained basically unchanged after an autotransplantation with 10% through 90% of the weight of the intact spleen. The phagocyte oxidative burst response was measured by chemiluminescence. The chemiluminescence response of these cells was reduced after a total splenectomy. The phagocyte oxidative burst response returned to normal levels following an autotransplantation. There was no correlation between the amount of autotransplanted spleen and the degree of the oxidative burst response. These findings indicated that a splenectomy results in a diminished phagocyte oxidative burst response and that a spleen autotransplantation returns this function to normal levels.