New York (CBS)  -- DEMOCRATS STUCK WITH DELEGATE DILEMMAS

It seems now there's no way for Michigan to have a do-over presidential primary.
 
"This is clearly an interparty issue for the state Democrat and national Democratic parties.  And it's just simply something that will not be resolved without them coming together and without the two candidates to come together to agree upon something," said State Senate Majority Leader Majority Leader Mike Bishop. He's a Republican, by the way.
 
But the candidates haven't come together on this.

Senator Obama has proposed splitting the Michigan and Florida delegates evenly with Senator Clinton.  She's behind in delegates.

"I do not understand what Senator Obama is afraid of, but it is going to hurt our party and our chances in November.  And so, I would call on him once again to join me in giving the people of Florida and Michigan the chance to be counted," said Sen. Hillary Clinton, Democrat of New York.
 
If there's no agreement, the superdelegates at the convention could very well decide the nomination.

"A CBS News Poll found that if Clinton wins the nomination, for example, thanks to the superdelegates, 92 percent of Obama's supporters would be angry or disappointed.  And if the reverse is true, if Obama wins the nomination thanks to the superdelegates, 73 percent of Clinton's supporters would be either angry or disappointed," said CBS News Correspondent Dean Reynolds. "There's very real concern that that alienation may be so great that the supporters of the losing candidate will just sit on their hands come November."

UNREST IN TIBET AND THE BEIJING OLYMPICS
 
Thousands of Chinese troops have converged on Tibetan areas of Western China, stepping up their manhunt for the anti-government protestors in Lhasa, Tibet's capital.

There was a violent crackdown there last week -- and, in neighboring provinces, protest demonstrations.  The Beijing government is now sending troops on foot, in trucks and helicopters to blanket a huge area, and they're warning tourists and foreign journalists to stay away. 

The Chinese government is blaming the Dalai Lama and his supporters for the violence.  Nancy Pelosi, the speaker of the U.S. House of Representative, is in India and met there today with the Dalai Lama.

"The situation in Tibet is a challenge to the conscience of the world," said Pelosi.
 
Secretary of State Condoleezza Rice has spoken with China's foreign minister.

"I hope that China will exercise restraint, but it is important that all parties refrain from violence," said Rice.

None of this has changed President Bush's plans to go the Olympics in Beijing.

Before Nancy Pelosi's meeting with the Dalai Lama today, calling on the world to protest the crackdown in Tibet, White House Press Secretary Dana Perino told reporters, "We are very concerned about what's happening in Tibet, and we have expressed those concerns. And that's something that President Bush and Secretary Rice can do that other citizens, concerned citizens around the world, are not able to do, just because they're not elected as a head of state."
 
In 1980, when the Soviet Union invaded Afghanistan, the U.S. pulled out of the Olympics in Moscow.  Jimmy Carter was President then. 
 
"If you're looking back in terms of 1980, I don't know if this President would have made that same decision, and we're not going to relitigate it.  But this President certainly hopes that our athletes who are training very hard have the best possible experience at the Olympics," said Perino.

REGROWING BODY PARTS

Three years ago, the propeller of a hobby shop airplane sliced off one of Lee Spievack's fingertips.  His brother Alan, a researcher in regenerative medicine, sent him a powder to sprinkle on it.
 
"And I powdered it on until it was covered," said Lee Spievack.

And lo and behold, the fingertip grew back.
 
CBS News Correspondent Wyatt Andrews has been working on a fascinating piece on regenerative medicine -- growing body parts.
 
The powder we were telling you about, as Dr. Steven Badylak explained to Wyatt Andrews, is called extracellular matrix.

"It tells the body to start that process of tissue regrowth", said Dr. Badylak.

Dr. Anthony Atala and his colleagues at Wake Forest University have built 18 different types of tissue including muscle, whole organs and the pulsing heart of a sheep.

"These cells are continuing to form new heart valve tissue.  When people ask me: What do you do?  We grow tissues and organs. We are making body parts that we can implant right back into patients," said Dr. Atala.

At the University of Pittsburgh Medical Center, adult stem cells are being injected into Mary Beth Babo's heart. She and her surgeon, Dr. Joon Lee, hope to grow new arteries.

"It's actually what we consider to be the Holy Grail of our field for coronary artery disease," said Dr. Lee.
 
"It's a big difference from open heart surgery to this.  If people don't have to go through that, this would be the way to go, if it works," said Babo.

Dr. Steven Nichtberger of Tengion Corporation said, "In regenerative medicine, I think it is similar to the semi-conductor industry of the 1980s.  You don't know where it's going to go, but you know it’s big."