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文内没提是那种干细胞,恐怕要上 The Lancet 才能找出来." l7 V; o( d) h' C3 Z
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Stemcells coaxed to rebuild bone, cartilage
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by (AFP) 6 O& |: I7 J, z7 @
& w/ U( P" Z- p+ x. U4 gPARIS — Scientists have shown for the first time that it may be possible to replace a human hip or knee with a joint grown naturally inside the body using the patient's stem cells.
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! q( _9 n# W* WIn experiments on rabbits, the researchers coaxed the animals' stem cells to rebuild the bone and cartilage of a missing leg joint, according to a study published on Thursday.
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( @4 b f$ E1 J"This is the first time an entire joint surface was regenerated with return of functions including weight bearing and locomotion," lead researcher Jeremy Mao, a professor at Columbia University Medical Center, said in a statement.
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: ~6 G6 M5 ~' vNaturally-grown joints would likely last longer than the current generation of artificial mechanisms, he said.
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7 f7 s# H+ M, l& @: i. HWith ageing populations and many people under 65 requiring replacement surgery, there is a real danger patients will outlive metallic joints and require a second gruelling operation late in life.
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In the experiments, Mao and colleagues removed the forelimb thigh joint of 10 rabbits, and then implanted a kind of scaffolding made of biologically compatible materials.) P3 q! Q) P* m2 A
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A naturally-occurring substance that stimulates cell growth then cued the rabbits' stemcells to go to the site of the missing joint and regenerate both cartilage and bone in two distinct layers.4 Q% d# K5 L+ m
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Within four weeks, the animals resumed normal movements -- a medical first, the researchers reported in the British medical journal The Lancet.
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% ^& r6 y: J$ |7 i; t4 BThe fact that the regenerated limb joint was created from the stem cells in the host animal -- rather than being harvested and then cultivated outside the body -- is also unprecedented, they said.
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) u$ l; Y$ U( }# l5 w: @1 xThis new procedure "may ultimately lead to clinical applications," said Mao. "In patients who need the knee, shoulder, hip or finger joints regenerated, the rabbit model provides a proof of principle."5 T/ }1 T( }$ a1 p
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But a number of scientific and regulatory issues remain before the procedure can be tested on humans, he said.) W; L7 Y3 d2 E6 g+ h
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For hip replacements, for example, recovery in people will be more difficult because humans carry all their weight on two legs.
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, M: k5 }5 d7 {; w- yMany patients are also likely to have existing conditions and drug regimens that could adversely affect the growth of new joints.; q: Y1 {+ u+ t( b8 \$ ^. c
5 |1 c. ^) z( r* v' c/ C0 CSome patients -- especially elderly people with diabetes -- will not have the same capacity for natural regeneration, cautioned Patrick Warnke of Australia's Bond University in a commentary, also in The Lancet.1 Q* A! F8 \, f$ [6 W' }
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The period of immobility while a joint regenerates also presents its own risks., m9 m, T5 f: `) J* Z/ c' V& j( n
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"The optimum way to grow a biological joint remains a controversy," Warnke said.5 T0 [# s0 {6 A- U( H v
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But, he added, the new research "offers a promising insight into what might be on the horizon."% O/ w; ]/ L4 I2 A- ^7 B
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As populations age in rich nations, the demand for total joint replacements has sky-rocketed.9 I) ?5 h. `+ X8 G' z, ^9 _
+ f, ~' @! ]% i/ a- ?: fIn the United States, more than 200,000 patients received total hip replacements in 2006, and nearly half a million got new knee joints, according to the US Nationwide Inpatient Sample database of hospital inpatient stays.8 x9 M: E* X" z9 S
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If these trends continue, an estimated 600,000 hip replacements and 1.4 million knee replacements will be carried out in 2015., j- C0 k! Q; ~$ m
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The United States accounts for 50 percent total procedures worldwide, with Europe accounting for 30 percent, according to Datamonitor.
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+ U: D7 Y) i. \; O. M Z5 f4 P+ WAn ageing population and increased incidence of obesity are primary causes for the increase in joint replacements. |
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发表于 2010-7-30 09:47
发表于 2010-7-30 10:45
发表于 2010-7-30 12:44
