MGC1 is a globular cluster about 65,000 light-years (about 200 kpc) away from the center of the Andromeda Galaxy, which is also known as M31. MGC1 is considered as one of the most isolated globular clusters in the Local Group (this title represents a group of galaxies including the Milky Way Galaxy, among others). It is actually closer to the Milky Way Galaxy than to the Andromeda Galaxy, but its radial velocity is statistically under the escape velocity of M31, therefore binding its gravity to it.
In 2010, three astronomers (Charlie Conroy, Abraham Loeb and David Spergel) submitted an article to The Astrophysical Journal, explaining with evidence how the two globular clusters MGC1 and NGC 2419, another globular cluster 30,000 light-years (90 kpc) away from the center of the Milky Way Galaxy, did not have dark matter halos surrounding them.
In another article submitted my the Acience Magazine, they interview Charlie Conroy explained "Using data obtained by other astronomers, the team created computer models of what globular clusters should look like in the presence and absence of dark matter halos. Over time, clusters without dark matter slowly lose their gravitational grip on the stars at their edges, the team found, whereas those with halos hold onto these stars. Both NGC 2419 and MGC1 are missing stars at their fringes, leading the researchers to conclude that they formed in the absence of dark matter halos. The same may be true of most globular clusters in the local universe."
This apparently proves that dark matter does not form all globular clusters, since the belief before this discovery was that dark matter helped form all globular clusters.