Alicja Wasiluk

Thrombopoiesis in small for gestational age newborns.

Thrombocytopenia in small for gestational age (SGA) newborns may be due to placental vascular pathology, fetal consumptive coagulopathy and platelet destruction, local imbalance of thromboxane A2 causing placental vasoconstriction and platelet aggregation. Thrombopoiesis in SGA newborns is poorly recognized. In 61 SGA newborns we evaluated thrombocytopoiesis in relation to gender and the rate maturity expressed as <5th percentile and <10th percentile. Female newborns demonstrated higher thrombopoietin (TPO) level at 92.06 pg/ml than male newborns at 79.81 pg/ml. Newborns less developed <5th percentile, showed increased TPO level of 92.0 pg/ml in comparison to <10th percentile of 78.0 pg/ml. This observation is more pronounced in female newborns. Contrary to our expectations we did not find any statistically significant differences in the percentage of reticulated platelets (PLRET) and platelets count in relation to gender and <5th percentile or <10th percentile. We can postulate intrauterine hypoxia is responsible for the increase of erythropoietin and impairment of thrombopoiesis in SGA newborns.

Does prematurity affect platelet indices

PURPOSE The current study objective was to compare blood platelet indices in preterm newborns (PTN) and full term newborns (FTN). MATERIALS AND METHODS We introduced to our study 51 PTN (25 females, 26 males) and 55 FTN (25 females, 30 males). Platelet indices were estimated in blood samples collected from the umbilical artery. RESULTS PTN demonstrated a decreased count of blood platelets (197 x 103/microL) as compared to FTN (287 x 103/microL), p=0.0001. Platelet hematocrit (PCT) also showed substantial differences in both groups (PTN=0.16% vs. FTN=0.22%; p=0.001). Mean platelet volume (MPV) was found to be nearly the same (PTN=8.02 fl, FTN=7.79 fl). Platelet distribution width (PDW) was higher in PTN (50.64%) than in FTN (46.54%), p=0.021. Large platelet count (LPLT) was diminished in PTN (5.23%) in comparison with FTN (6.12 %). CONCLUSIONS A decreased count of blood platelets, platelet hematocrit and increased platelet distribution width may result from a low gestational age or a dysfunction of megakaryocytes and the placenta. Blood platelet indices may be vital in the diagnosis of haemostatic disorders.

The effect of gestational age on platelet surface expression of CD62P in preterm newborns.

Hemostasis in preterm newborns is characterized by low reserve functional capacity with special reference to the presence of such risk factors as asphyxia or infection. Platelets play vitally important role in hemostasis. Expression of CD62P is a marker of stimulated or activated blood platelets. The study involved a group of 16 preterm newborns, five girls and 11 boys. DAKO QIFIKIT was applied to calculate the number of these antigens. The mean CD 62P expression was found to be 23 792 per platelet. Correlation was found between antigen density and gestational age r = 0.954, p = 0.01. Evident deficit of P-selectin on the surface of platelets in preterm newborns may be at least in part responsible for platelet dysfunction, with special reference to interaction between circulating leukocytes and combating infection.

Markers of platelets activation, CD 62P and soluble P-selectin in healthy term neonates.

Abstract Nearly the same expression of CD 62P antigen was found on the platelets of neonates in the vein as in the artery, in both females and males. SP-selectin concentrations in sera were elevated in the vein in comparison to the artery, higher values being noted in females than in males. The activation of platelets occurs at the time of birth. The platelets of female neonates are more activated than those of male neonates.

Platelet indices in SGA newborns

PURPOSE The current study objective was to compare blood platelet indices in full-term small-for-gestational-age newborns (SGA) and full-term appropriate-for-gestational-age newborns (AGA). MATERIALS/METHODS We introduced to our study 61 SGA newborns (31 females and 30 males) and 70 eutrophic infants (32 females and 38 males). The SGA newborns were divided into two groups: those weighing less than the 5th centile: 35 infants (16 females and 19 males) and those between the 5th and 10th centiles: 26 infants (15 females and 11 males). Platelet indices were estimated in blood samples collected from the umbilical artery. RESULTS SGA demonstrated a decreased count of blood platelets (238×103/μ) as compared with AGA (286×103/μL), p=0.0001. Platelet hematocrit (PTC) also showed differences in both groups (SGA=0.19% vs. AGA=0.22%; p=0.0005). Mean platelet volume (MPV) was higher in SGA (8.25fl) as compared with AGA (7.84fl); p=0.008. Large platelet count (LPLT) was higher in AGA 6.26% vs. SGA=4.75%; p=0.01. Platelet distribution width (PDW) was found to be nearly the same (SGA=47%, AGA=46%). PDW was higher in SGA newborns < 5th centile (43%) as compared with SGA infants between the 5th and 10th centiles (52%); p=0.008. CONCLUSIONS A decreased blood platelet count, platelet hematocrit and large metabolically active platelet count, which in addition to reduced synthesis and excessive consumption of coagulation factors in states of hiperclotting is characteristic of IUGR, enhances the possibility of bleeding complications and increases the risk of infections. From a clinical point of view, it is important to take into consideration the degree of intrauterine hypotrophy during the evaluation of hemostatic disorders.

Thrombocytopoiesis in healthy term newborns

Abstract Aims: Thrombocytopoiesis was investigated in term newborns determining thrombopoietin (TPO), reticulated platelets (PLRET) and blood platelets (PLT) in relation to gender. Patients and methods: The study was undertaken on 72 healthy term newborns, 33 girls and 39 boys. They fitted all criteria for healthy term newborns. Blood was collected from the umbilical vein immediately after cutting the umbilical cord. The evaluation of thrombocytopoiesis was performed by the following methods: TPO–Quantikine human TPO kit, PLRET– Retic-Count kit, PLT– Advia™ 120 hematology System. Results: Concentrations of TPO and percentages of reticulated platelets were greater in the female group than in the male group. The changes were not statistically significant, perhaps as a result of the very wide range of parameters tested. The blood platelet count was higher in female newborns than in male newborns, P<0.001. Conclusion: The data may indicate that thrombocytopoiesis is more active in female than in male newborns.

Expression of P-selectin (CD62P) on platelets after thrombin and ADP in hypotrophic and healthy, full-term newborns

Abstract Background: Hypotrophic newborns in comparison with eutrophic newborns demonstrate a reduced blood platelet count and therefore may have haemostasis disorders. Expression of P-selectin (CD62P) on the surface of platelets is a marker of stimulated, activated blood platelets. The ability of platelets to react can be determined after the addition of the following activators: strong (thrombin) and weak (ADP). Materials and methods: We studied 48 hypotrophic newborns, 25 females and 23 males, weighing less than the 10th centile and 55 healthy, full-term newborns, 25 females and 30 males. Expression of CD62P on the surface of platelets was examined in the native state, after the addition of thrombin or ADP. Results: Hypotrophic newborns exhibited almost double the percentage of platelets expressing CD62P compared with the control group, 4.21% versus 2.88%. After the addition of thrombin, the percentage was 31.5% versus 12.5%, p < 0.001, whereas after the addition of ADP, the percentage was 9.54% versus 4.5%, p = 0.002. Conclusions: Hypotrophic newborns are capable of greater platelet activation in comparison with healthy term newborns. However, gender does not affect the expression of P-selectin.

Platelet-Derived Microparticles and Platelet Count in Preterm Newborns

Objective: Does formation of platelet-derived microparticles correspond to platelet activation? Methods: The study was performed in 51 preterm newborns, 25 girls and 26 boys. The control group consisted of 55 term newborns, 25 girls and 30 boys. Blood samples were collected from the umbilical artery. The percentage of platelet-derived microparticles and platelet count were determined using flow cytometric analysis based on the CD61-positive antigen. Results: The percentage of platelet-derived microparticles was higher in preterm newborns (5.46) in comparison to term newborns (4.22, p < 0.01). We found 4.61% of platelet-derived microparticles in preterm female newborns and 6.28% in preterm boys (p < 0.0070). The platelet count was 256 × 103 µl in girls and 238 × 103 µl in boys. Female healthy term newborns presented higher values of platelet-derived microparticles (4.4%) than male newborns (4.07%, p = 0.4725, table 1). The platelet count in girls was found to be 308 × 103 µl and in boys 270 × 103 µl. Conclusions: Higher percentage of platelet-derived microparticles in preterm newborns may provide a compensatory mechanism for the hemostatic system.

Antigen density of P-selectin (CD 62P) on the platelets of healthy term newborns

Measurements have been made of the antigen density of P-selectin (CD 62P) on the surface of platelets of healthy term newborns in relation to sex and in different umbilical vessels. The effect of thrombin or ADP on the density of CD 62P has been determined. The study was performed in 18 healthy term newborns, 10 girls and eight boys. Dako QIFIKIT was applied to calculate the number of these antigens. No differences were observed in the number of antigens of CD 62P on newborn platelets between the umbilical vein and artery in both sexes. On the other hand, boys demonstrated 31 245 antigens/plt, girls 26 397/plt (P = 0.045). A statistically significant increase in the expression of CD 62P was also observed following activation of thrombin in both sexes and in the umbilical vein and artery. ADP as a weaker agonist demonstrated less changes. A high number of the CD 62P antigens on the platelets of newborns may be interpreted as an effect of increased thrombinogenesis during birth. It can be suggested that this process is more pronounced in boys than girls.

Does prematurity affect thrombocytopoiesis

Data concerning thrombocytopoiesis in newborns are poorly recognized. Platelets have a crucial role in hemostatic physiology, which is deficient in newborns, especially in preterm newborns. A total of 51 preterm newborns (PTN), 25 girls and 26 boys, were recruited for the study. The control group consisted of 25 female and 30 male healthy term newborns (HTN). Plasma thrombopoietin (TPO) was measured using Quantikine human TPO system. Reticulated platelets (PLRET) was estimated by means of Retic-Count Kit. Platelet count (PLT) was determined using AdviaTU 120 Hematology System. TPO was evidently higher in PTN (110.9 pg/ml) than in HTN (71.5 pg/ml), (p < 0.001). The percentage of reticulated platelets (PLRET) was also twice as high in PTN (3.49%) in comparison to HTN (1.7%), (p < 0.001). The PLT count was lower in PTN (246.7 × 103 µL) than in HTN (287.2 × 103 µL), (p < 0.01). Increased TPO levels and the percentage of PLRET indicate that thrombocytopoiesis is more active in prematurity. Our finding may be useful in therapeutic strategies.