Platelet microparticles: Detection and assessment of their paradoxical functional roles in disease and regenerative medicine

There is increasing research on and clinical interest in the physiological role played by platelet microparticles (PMPs). PMPs are 0.1–1-μm fragments shed from plasma membranes of platelets that are undergoing activation, stress, or apoptosis. They have a phospholipid-based structure and express functional receptors from platelet membranes. As they are the most abundant microparticles in the blood and they express the procoagulant phosphatidylserine, PMPs likely complement, if not amplify, the functions of platelets in hemostasis, thrombosis, cancer, and inflammation, but also act as promoters of tissue regeneration. Their size and structure make them instrumental in platelet–cell communications as a delivery tool of platelet-borne bioactive molecules including growth factors, other signaling molecules and micro (mi)RNA. PMPs can therefore be a pathophysiological threat or benefit to the cellular environment when interacting with the blood vasculature. There is also increasing evidence that PMP generation is triggered during blood collection, separation into components, and storage, a phenomenon potentially leading to thrombotic and inflammatory side effects in transfused patients. Evaluating PMPs requires strict pre-analytical and analytical procedures to avoid artifactual generation and ensure accurate assessment of the number, size repartitioning, and functional properties. This review describes the physical and functional methods developed for analyzing and quantifying PMPs. It then presents the functional roles of PMPs as markers or triggers of diseases like thrombosis, atherosclerosis, and cancer, and discusses the possible detrimental immunological impact of their generation in blood components. Finally we review the potential function of PMPs in tissue regeneration and the prospects for their use in therapeutic strategies for human health.     

Acute deterioration of Charcot-Marie-Tooth disease IA (CMT IA) following 2 mg of vincristine chemotherapy.

Background:Severe up to life-threatening neuropathy has beenobserved in patients with hereditary neuropathies receiving vincristine. Case report:A 52-year-old female painter suffering fromhigh-grade non-Hodgkin's lymphoma (stage IVB) was treated with a total of 4mg of vincristine during two courses of CHOP chemotherapy (cyclophosphamide,vincristine, adriamycin, prednisone). At onset of treatment no neurologicalproblems were reported. There was good lymphoma response to chemotherapy. Atthe same time, however, the patient gradually developed dysphagia, dysarthria,muscular weakness of both lower and upper extremities, areflexia, paraesthesiaof the fingertips and bilateral sensory impairment of feet and lower legs.These symptoms continually worsened over a period of seven weeks until she wasunable to walk or to perform her work. Electrophysiological studies showedperipheral axonal and demyelinative sensorimotor neuropathy in correlation tohistological findings. Molecular analysis revealed 17p11.2 duplication typicalfor Charcot–Marie–Tooth disease IA. While continuing chemotherapywithout the use of vincristine the patient's neurologic symptoms slowlyrecovered within six months. Conclusion:Prior to administration of vincristine family andpatient history as well as physical examination should be performed carefullyto look for underlying hereditary neuropathy. For those patients with aclinical history or symptoms suggestive for CMT nerve conduction velocitystudies and on an individual base even molecular genetic analysis areneccessary to prevent serious neurologic complications.     

Spectrum of mutations in Finnish patients with Charcot-Marie-Tooth disease and related neuropathies

Our patient material included families and sporadic patients of Finnish origin with the diagnosis of Charcot-Marie-Tooth (CMT) disease types 1 and 2, Déjérine-Sottas syndrome (DSS), and hereditary neuropathy with liability to pressure palsies (HNPP). We screened for mutations in the peripheral myelin protein genes connexin 32 (Cx32), myelin protein zero (P₀) and peripheral myelin protein 22 (PMP22) by direct sequencing. All patients chosen for mutation screening were negative for the 1.5 Mb duplication/deletion at 17p11.2-p12. Eleven Cx32 mutations were found in 12 families, six with a CMT2 diagnosis, three with a CMT1 diagnosis and three with unclassified CMT. The total number of patients in these 12 CMTX families was 61, giving a minimum prevalence of 1.2/100,000 for CMTX in Finland. Four of the mutations, Pro58Arg, Pro172Leu, Asn175Asp and Leu204Phe, have not been previously reported. One male patient with an early onset CMT had a double Cx32 mutation, Arg22Gln and Val63Ile. The double de novo mutation was found to be of maternal grandpaternal origin. In the P₀ gene a Ser78Leu mutation was found in one family with severe CMT1 and a de novo Tyr82Cys mutation was found in one DSS patient. Both mutations have been previously reported in other CMT1 families. A novel PMP22 mutation, deletion of Phe84, was found in one sporadic DSS patient. Our mutation screening results show the necessity of molecular diagnosis, in addition to clinical and electrophysiological evaluation, for proper subtyping of the disease and for accurate genetic counseling. Hum Mutat 12:59–68, 1998. © 1998 Wiley-Liss, Inc.     

河南地区两个腓骨肌萎缩症家系PMP22基因突变研究

目的分析在河南地区两个腓骨肌萎缩症(CMT)家系的临床表现及PMP22基因重复突变的特点。方法收集两家系中21名成员的临床资料,并应用等位基因特异性PCR-双酶切方法检测17p11.2-1 PMP22基因重复(即1760 bp片段)序列的情况,同时选择50名健康人做为对照。结果两家系中共14名成员经等位基因特异性PCR-双酶切方法检测出PMP22基因大片重复(即1760 bp片段)序列;家系一患病者有3名(Ⅱ5、Ⅱ7、Ⅲ11),无临床症状但基因检测结果示PMP22基因重复突变为携带者有6名(Ⅱ9、Ⅲ6、Ⅲ8、Ⅲ10、Ⅳ1、Ⅳ2);家系二患病者有4名(Ⅱ3、Ⅱ9、Ⅱ11、Ⅲ7),携带者只有Ⅲ5。两家系中余7人及健康对照50人均未检测出上述重复突变。结论 PCR-双酶切法检测PMP22特异性基因重复序列在早期诊断CMT有重要价值。