Potential regenerative applications of human placental mesenchymal stem cells

 

Dr. Mohammad Fatum (PI) - TRDC

Dr. Mankuta David - Hadassah Hospital

 

  Background

Human mesenchymal stem cells (MSC ) are non-hematopoietic multipotent stem cells that are able to differentiate along different pathways including the osteogenic, adipogenic, and chondrogenic lineages (Caplan Al (1994), Pittenger MF and al (1999), Bianco P and al (2000), Deans RJ (2000), Prockop DJ (1997). MSC can be isolated from various sources : they were first isolated from Bone-marrow (Friederstein AJ and al, (1976); Caplan (1991), and subsequently isolated from other tissues such as adipose tissue, cutaneous tissue , fetal hepatic and pulmonary tissues (Williams and al, 1999; Warejcka and al 1996, Gronthos and al, 1999; Grigoriadis and al 1998; Lancar D and al, 1992 , Romanov and al,2003, Campagnoli and al, 2001, Erices and al, 2000, Moreschy and al. 2001).

Clinical use of MSCs is far from routine practice, but as an innovative procedure they do show their potential in engraftment of autologous and allogeneic bone marrow, in treatment of GvHD , in treatment of genetic diseases (Horowitz  1999) in  bone and cartilage disorders  (Aslan H 2006)( Pelled G) (Chen and al 2006 ), and in  CNS disorders. Because MSCs have unique immunologic characteristics that suppress lymphocytes proliferation in vitro, they were used to prolong skin graft survival in vivo  (Bartholomew 2002).

Currently, the most common source of MSC has been the bone marrow. However, aspirating the bone-marrow from the patient is still an invasive procedure. Moreover, the number of MSCs from BM decreases with age. Thus, the search for possible alternative MSC sources remains to be necessary.

 In perinatal medicine, MSCs from the placenta could be clinically used as autologous grafts for fetuses and newborns in peripartum tissue regeneration or for in utero transplantation in case of genetic disorders and fetal morphological malformations. An obvious advantage is the lack of  immunologic rejection by the recipient .  Furthermore, compared with allogeneic embryonic stem cells, ethical concerns and concerns regarding rejection could be circumvented (Surbek 2001) .

Fetal malformations that could potentially be corrected by MSC transplantation could be :

Open CNS disorders: Meningomeylocele ,encephalocele which are associated with significant morbidity .These disorders could be theoretically corrected if MSC could be implanted in the area of the opening in the CNS and would closed the orifice. MSC from amniotic fluid has been used to enhance the regeneration of an injured sciatic nerve (Hung-Chuan Pan 2006)

Another example  of a  birth defects is congenital diaphragmatic hernia. This disease is associated with high postnatal mortality and morbidity.  MSC  could be used to repair the hernia during the pregnancy. Such an  approach was tested in neonatal lambs that underwent repair of an  experimental diaphragmatic defect with identical scaffolds, either seeded  with labeled autologous cells (Kunisaki SM,2006).

 Preterm premature rupture of membranes (PROM) is a clinical problem that affects about 2 % of all the pregnancies but it contributed to 20 percent of all

perinatal deaths. (Cox et al 1988) . The time period from preterm rupture of  membranes to delivery is inversely proportional to the gestational age when

the membranes rupture.  Very few days were gained when membranes ruptured during the third trimester compared with the second trimester. Maternal and fetal risks vary with the gestational age at membrane rupture and include the consequences of uterine infection and sepsis. When contemplating expectant management before 25 weeks, additional consideration is given to fetal risks of oligohydramnios with resultant pulmonary hypoplasia and limb compression deformities. Iatrogenic PROM is a major limitation of uterine endoscopy; the incidence is  10% after laser coagulation for twin-twin transfusion syndrome , >30% after fetoscopic cord ligation and > 62% after endoscopic tracheal clipping .

Most  research has concentrated on the pathogenesis of PROM  while largely neglecting the repair and healing potential of fetal membranes. The association  of changes in the secretion of matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors (TIMPs) with the restoration of fetal membrane integrity in an animal model following fetoscopy suggests an active repair process . Clinical experience also supports the hypothesis of fetal  membrane repair given the very low incidence of PROM after routine midtrimester amniocentesis  and the spontaneous "resealing" reported  in 7.7% to 9.7% cases of PROM.( Schucker JL 1996) Attempts were done in order to repair the broken membranes . Several treatments were used: from collagen plugs in a rabbit model ,to amniopatch, amniograft , maternal blood clot patch  and fibrin glue in humans.

A set of a gelatin  sponge for cervical plugging was described by O'Brien and colleagues (2002) in 15 women with early midtrimester  membrane rupture. These  techniques  are  still investigational. However, cell-based or tissue-engineered therapies, e.g. using cartilage, Endothelium or skin, have since become an alternative and promising option after injury in many branches of medicine.

The purpose of this study is to isolate human mesenchymal  stem cells from placenta and from the umbilical cord and then to develop a method  to restoring the fetal membrane integrity after PROM and in open fetal  CNS open defects malformationss This ill be done by trying to seal an iatrogenic hole performed in term and preterm human membranes and open CNS defects,with cultured placental  mesanchymal cells.  We aim further to characterize the optimal medium for the growth of amniotic  MSC .