We have identified an easily attainable source of primitive, potentially multipotent stem cells from Wharton's jelly, the matrix of umbilical cord. Wharton's jelly cells have been propagated in culture for more than 80 population doublings. Several markers for stem cells, including c-kit (CD117), and telomerase activity are expressed in these cells. Treatment with basic fibroblast growth factor overnight and low-serum media plus butylated hydroxyanisole and dimethylsulfoxide induced Wharton's jelly cells to express a neural phenotype. Within several hours of this treatment, Wharton's jelly cells developed rounded cell bodies with multiple neurite-like extensions, similar to the morphology of neural stem cells. Neuron-specific enolase (NSE), a neural stem cell marker, was expressed in these cells, as shown by immunocytochemistry. Immunoblot analysis showed similar levels of NSE expression in both untreated and induced Wharton's jelly cells. After 3 days, the induced Wharton's jelly cells resembled bipolar or multipolar neurons, with processes that formed networks reminiscent of primary cultures of neurons. The neuron-like cells in these cultures stained positively for several neuronal proteins, including neuron-specific class III beta-tubulin, neurofilament M, an axonal growth-cone-associated protein, and tyrosine hydroxylase. Immunoblot analysis showed increasing levels of protein markers for mature neurons over time post induction. Markers for oligodendrocytes and astrocytes were also detected in Wharton's jelly cells. These exciting findings show that cells from the matrix of umbilical cord have properties of stem cells and may, thus, be a rich source of primitive cells. This study shows their capacity to differentiate into a neural phenotype in vitro.

Receptor-like proteins (RLPs) are cell surface receptors that typically consist of an extracellular leucine-rich repeat domain, a transmembrane domain, and a short cytoplasmatic tail. In several plant species, RLPs have been found to play a role in disease resistance, such as the tomato (Solanum lycopersicum) Cf and Ve proteins and the apple (Malus domestica) HcrVf2 protein that mediate resistance against the fungal pathogens Cladosporium fulvum, Verticillium spp., and Venturia inaequalis, respectively. In addition, RLPs play a role in plant development; Arabidopsis (Arabidopsis thaliana) TOO MANY MOUTHS (TMM) regulates stomatal distribution, while Arabidopsis CLAVATA2 (CLV2) and its functional maize (Zea mays) ortholog FASCINATED EAR2 regulate meristem maintenance. In total, 57 RLP genes have been identified in the Arabidopsis genome and a genome-wide collection of T-DNA insertion lines was assembled. This collection was functionally analyzed with respect to plant growth and development and sensitivity to various stress responses, including susceptibility toward pathogens. A number of novel developmental phenotypes were revealed for our CLV2 and TMM insertion mutants. In addition, one AtRLP gene was found to mediate abscisic acid sensitivity and another AtRLP gene was found to influence nonhost resistance toward Pseudomonas syringae pv phaseolicola. This genome-wide collection of Arabidopsis RLP gene T-DNA insertion mutants provides a tool for future investigations into the biological roles of RLPs.For decades, it was thought that the communication between plant cells occurs through the cell wall-spanning cytoplasmic bridges called plasmodesmata. However, since the identification of the first plant cell surface receptor (Walker and Zhang, 1990), it has been known that, similar to other multicellular organisms, plants can perceive extracellular signals at the plasma membrane. Since then, many plant cell surface receptors have been found to play key roles in very diverse processes ranging from growth and development, in which they perceive endogenous self signals, to recognition of other organisms, in which they perceive exogenous nonself signals (Diévart and Clark, 2004).A common structural element of many plant cell surface receptors is the extracellular Leu-rich repeat (eLRR) domain that is generally thought to mediate ligand perception (Kobe and Kajava, 2001;Kinoshita et al., 2005). These eLRRs are composed of 23 to 25 amino acids with the conserved consensus sequence LxxLxxLxLxxNxLt/sgxIpxxLG (Jones and Jones, 1997). The largest group of eLRR-containing cell surface receptors is formed by the receptor-like kinases (RLKs) that are composed of an eLRR domain, a single-pass transmembrane domain, and a cytoplasmic kinase domain, with over 200 representatives in the Arabidopsis (Arabidopsis thaliana) genome (Shiu and Bleecker, 2003). The second largest group of eLRR-containing cell surface receptors is formed by the receptor-like proteins (RLPs) that differ from RLKs in that they lack the cytoplasmic kinase domai...